Default installation script doesn't set HOMEBREW_PREFIX to usr/local

gistfile1.txt

brew config

HOMEBREW_VERSION: 1.0.6
ORIGIN: https://github.com/Homebrew/brew
HEAD: 35ee2831086e923e7fcaf75fb440b01312e3f9c5
Last commit: 5 days ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: ff01a46baddadcb0f24638252ff59e25d048a792
Core tap last commit: 2 hours ago
HOMEBREW_PREFIX: /usr/local/homebrew
HOMEBREW_REPOSITORY: /usr/local/homebrew
HOMEBREW_CELLAR: /usr/local/homebrew/Cellar
HOMEBREW_BOTTLE_DOMAIN: https://homebrew.bintray.com
CPU: quad-core 64-bit broadwell
Homebrew Ruby: 2.0.0-p648
Clang: 7.3 build 703
Git: 2.6.2 => /usr/local/bin/git
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
Java: 1.8.0_92, 1.8.0_60
macOS: 10.11.6-x86_64
Xcode: N/A
CLT: 7.3.1.0.1.1461711523
X11: 2.7.8 => /opt/X11

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry and just ignore them. Thanks!

Warning: Your XQuartz (2.7.8) is outdated.
Please install XQuartz 2.7.9 (or delete it):
  https://xquartz.macosforge.org

Warning: Python is installed at /Library/Frameworks/Python.framework

Homebrew only supports building against the System-provided Python or a
brewed Python. In particular, Pythons installed to /Library can interfere
with other software installs.

Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected dylibs:
    /usr/local/lib/libtcl8.6.dylib
    /usr/local/lib/libtk8.6.dylib

Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected header files:
    /usr/local/include/fakemysql.h
    /usr/local/include/fakepq.h
    /usr/local/include/fakesql.h
    /usr/local/include/itcl.h
    /usr/local/include/itcl2TclOO.h
    /usr/local/include/itclDecls.h
    /usr/local/include/itclInt.h
    /usr/local/include/itclIntDecls.h
    /usr/local/include/itclMigrate2TclCore.h
    /usr/local/include/itclTclIntStubsFcn.h
    /usr/local/include/mysqlStubs.h
    /usr/local/include/node/android-ifaddrs.h
    /usr/local/include/node/ares.h
    /usr/local/include/node/ares_version.h
    /usr/local/include/node/libplatform/libplatform.h
    /usr/local/include/node/nameser.h
    /usr/local/include/node/node.h
    /usr/local/include/node/node_buffer.h
    /usr/local/include/node/node_internals.h
    /usr/local/include/node/node_object_wrap.h
    /usr/local/include/node/node_version.h
    /usr/local/include/node/openssl/aes.h
    /usr/local/include/node/openssl/archs/aix-gcc/opensslconf.h
    /usr/local/include/node/openssl/archs/aix64-gcc/opensslconf.h
    /usr/local/include/node/openssl/archs/BSD-x86/opensslconf.h
    /usr/local/include/node/openssl/archs/BSD-x86_64/opensslconf.h
    /usr/local/include/node/openssl/archs/darwin-i386-cc/opensslconf.h
    /usr/local/include/node/openssl/archs/darwin64-x86_64-cc/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-aarch64/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-armv4/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-elf/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-ppc/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-ppc64/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-x32/opensslconf.h
    /usr/local/include/node/openssl/archs/linux-x86_64/opensslconf.h
    /usr/local/include/node/openssl/archs/solaris-x86-gcc/opensslconf.h
    /usr/local/include/node/openssl/archs/solaris64-x86_64-gcc/opensslconf.h
    /usr/local/include/node/openssl/archs/VC-WIN32/opensslconf.h
    /usr/local/include/node/openssl/archs/VC-WIN64A/opensslconf.h
    /usr/local/include/node/openssl/asn1.h
    /usr/local/include/node/openssl/asn1_mac.h
    /usr/local/include/node/openssl/asn1t.h
    /usr/local/include/node/openssl/bio.h
    /usr/local/include/node/openssl/blowfish.h
    /usr/local/include/node/openssl/bn.h
    /usr/local/include/node/openssl/buffer.h
    /usr/local/include/node/openssl/camellia.h
    /usr/local/include/node/openssl/cast.h
    /usr/local/include/node/openssl/cmac.h
    /usr/local/include/node/openssl/cms.h
    /usr/local/include/node/openssl/comp.h
    /usr/local/include/node/openssl/conf.h
    /usr/local/include/node/openssl/conf_api.h
    /usr/local/include/node/openssl/crypto.h
    /usr/local/include/node/openssl/des.h
    /usr/local/include/node/openssl/des_old.h
    /usr/local/include/node/openssl/dh.h
    /usr/local/include/node/openssl/dsa.h
    /usr/local/include/node/openssl/dso.h
    /usr/local/include/node/openssl/dtls1.h
    /usr/local/include/node/openssl/e_os2.h
    /usr/local/include/node/openssl/ebcdic.h
    /usr/local/include/node/openssl/ec.h
    /usr/local/include/node/openssl/ecdh.h
    /usr/local/include/node/openssl/ecdsa.h
    /usr/local/include/node/openssl/engine.h
    /usr/local/include/node/openssl/err.h
    /usr/local/include/node/openssl/evp.h
    /usr/local/include/node/openssl/hmac.h
    /usr/local/include/node/openssl/idea.h
    /usr/local/include/node/openssl/krb5_asn.h
    /usr/local/include/node/openssl/kssl.h
    /usr/local/include/node/openssl/lhash.h
    /usr/local/include/node/openssl/md4.h
    /usr/local/include/node/openssl/md5.h
    /usr/local/include/node/openssl/mdc2.h
    /usr/local/include/node/openssl/modes.h
    /usr/local/include/node/openssl/obj_mac.h
    /usr/local/include/node/openssl/objects.h
    /usr/local/include/node/openssl/ocsp.h
    /usr/local/include/node/openssl/opensslconf.h
    /usr/local/include/node/openssl/opensslv.h
    /usr/local/include/node/openssl/ossl_typ.h
    /usr/local/include/node/openssl/pem.h
    /usr/local/include/node/openssl/pem2.h
    /usr/local/include/node/openssl/pkcs12.h
    /usr/local/include/node/openssl/pkcs7.h
    /usr/local/include/node/openssl/pqueue.h
    /usr/local/include/node/openssl/rand.h
    /usr/local/include/node/openssl/rc2.h
    /usr/local/include/node/openssl/rc4.h
    /usr/local/include/node/openssl/ripemd.h
    /usr/local/include/node/openssl/rsa.h
    /usr/local/include/node/openssl/safestack.h
    /usr/local/include/node/openssl/seed.h
    /usr/local/include/node/openssl/sha.h
    /usr/local/include/node/openssl/srp.h
    /usr/local/include/node/openssl/srtp.h
    /usr/local/include/node/openssl/ssl.h
    /usr/local/include/node/openssl/ssl2.h
    /usr/local/include/node/openssl/ssl23.h
    /usr/local/include/node/openssl/ssl3.h
    /usr/local/include/node/openssl/stack.h
    /usr/local/include/node/openssl/symhacks.h
    /usr/local/include/node/openssl/tls1.h
    /usr/local/include/node/openssl/ts.h
    /usr/local/include/node/openssl/txt_db.h
    /usr/local/include/node/openssl/ui.h
    /usr/local/include/node/openssl/ui_compat.h
    /usr/local/include/node/openssl/whrlpool.h
    /usr/local/include/node/openssl/x509.h
    /usr/local/include/node/openssl/x509_vfy.h
    /usr/local/include/node/openssl/x509v3.h
    /usr/local/include/node/pthread-fixes.h
    /usr/local/include/node/stdint-msvc2008.h
    /usr/local/include/node/tree.h
    /usr/local/include/node/uv-aix.h
    /usr/local/include/node/uv-bsd.h
    /usr/local/include/node/uv-darwin.h
    /usr/local/include/node/uv-errno.h
    /usr/local/include/node/uv-linux.h
    /usr/local/include/node/uv-sunos.h
    /usr/local/include/node/uv-threadpool.h
    /usr/local/include/node/uv-unix.h
    /usr/local/include/node/uv-version.h
    /usr/local/include/node/uv-win.h
    /usr/local/include/node/uv.h
    /usr/local/include/node/v8-debug.h
    /usr/local/include/node/v8-platform.h
    /usr/local/include/node/v8-profiler.h
    /usr/local/include/node/v8-testing.h
    /usr/local/include/node/v8-util.h
    /usr/local/include/node/v8-version.h
    /usr/local/include/node/v8.h
    /usr/local/include/node/v8config.h
    /usr/local/include/node/zconf.h
    /usr/local/include/node/zlib.h
    /usr/local/include/odbcStubs.h
    /usr/local/include/pqStubs.h
    /usr/local/include/tcl.h
    /usr/local/include/tclDecls.h
    /usr/local/include/tclOO.h
    /usr/local/include/tclOODecls.h
    /usr/local/include/tclPlatDecls.h
    /usr/local/include/tclThread.h
    /usr/local/include/tclTomMath.h
    /usr/local/include/tclTomMathDecls.h
    /usr/local/include/tdbc.h
    /usr/local/include/tdbcDecls.h
    /usr/local/include/tdbcInt.h
    /usr/local/include/tk.h
    /usr/local/include/tkDecls.h
    /usr/local/include/tkPlatDecls.h

Warning: Unbrewed .pc files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected .pc files:
    /usr/local/lib/pkgconfig/tcl.pc
    /usr/local/lib/pkgconfig/tk.pc

Warning: Unbrewed static libraries were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected static libraries:
    /usr/local/lib/libtclstub8.6.a
    /usr/local/lib/libtkstub8.6.a

Warning: Your Homebrew's prefix is not /usr/local.
You can install Homebrew anywhere you want but some bottles (binary packages)
can only be used with a /usr/local prefix and some formulae (packages)
may not build correctly with a non-/usr/local prefix.