Problem with brew

brew config

⋊> /u/local on master  brew config                                                                                         10:25:11
HOMEBREW_VERSION: 0.9.9
ORIGIN: https://github.com/Homebrew/brew.git
HEAD: ca005cb8245e7e12ad808d78d49bce3953e1153c
Last commit: 65 minutes ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: 351775d67b2e8145ac665e53ea467cff894473fa
Core tap last commit: 5 hours ago
HOMEBREW_PREFIX: /usr/local
HOMEBREW_REPOSITORY: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
HOMEBREW_BOTTLE_DOMAIN: https://homebrew.bintray.com
CPU: octa-core 64-bit haswell
Clang: 7.3 build 703
Git: 2.9.0 => /usr/local/bin/git
Perl: /usr/bin/perl
Python: /usr/local/bin/python => /usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/bin/python2.7
Ruby: /usr/local/bin/ruby => /usr/local/Cellar/ruby/2.3.1/bin/ruby
Java: 1.8.0_74, 1.7.0_80
System Ruby: 2.0.0-p648
OS X: 10.11.4-x86_64
Xcode: 7.3.1
CLT: 7.3.1.0.1.1461711523
X11: N/A

brew doctor

⋊> /u/local on master  brew doctor                                                                                         10:24:14
Error: undefined method `include?' for nil:NilClass
Please report this bug:
    https://git.io/brew-troubleshooting
/usr/local/Library/Homebrew/extend/os/mac/diagnostic.rb:317:in `check_for_beta_xquartz'
/usr/local/Library/Homebrew/cmd/doctor.rb:42:in `block in doctor'
/usr/local/Library/Homebrew/cmd/doctor.rb:35:in `each'
/usr/local/Library/Homebrew/cmd/doctor.rb:35:in `doctor'
/usr/local/Library/brew.rb:87:in `<main>'

xcode-select --install

⋊> /u/local on master  xcode-select --install                                                                              10:27:10
xcode-select: error: command line tools are already installed, use "Software Update" to install updates