bcrypt-ruby bc_salt segfault

ruby-2.5.txt

-- C level backtrace information -------------------------------------------
/opt/ruby2.5.1/bin/../lib/libruby.so.2.5(rb_vm_bugreport+0x974) [0x7f6e7aad0904]
/opt/ruby2.5.1/bin/../lib/libruby.so.2.5(0xaaec4) [0x7f6e7a941ec4]
/opt/ruby2.5.1/bin/../lib/libruby.so.2.5(0x1a89c2) [0x7f6e7aa3f9c2]
/lib/x86_64-linux-gnu/libc.so.6(0x7f6e7a4e4f20) [0x7f6e7a4e4f20]
/lib/x86_64-linux-gnu/libc.so.6(__strlen_avx2+0x11) [0x7f6e7a6345a1] ../sysdeps/x86_64/multiarch/strlen-avx2.S:59
/opt/ruby2.5.1/bin/../lib/libruby.so.2.5(rb_str_new_cstr+0xe) [0x7f6e7aa5712e]
/u/apps/bc3/shared/bundle-ruby221/ruby/2.5.0/gems/bcrypt-3.1.13/lib/bcrypt_ext.so(bc_salt+0x6a) [0x7f6e6ad2b04a]

ruby-2.6.txt

-- C level backtrace information -------------------------------------------
/opt/ruby2.6.1/bin/../lib/libruby.so.2.6(rb_vm_bugreport+0x974) [0x7f8350d43ca4] vm_dump.c:715
/opt/ruby2.6.1/bin/../lib/libruby.so.2.6(rb_bug_context+0xe7) [0x7f8350b87fd7] error.c:609
/opt/ruby2.6.1/bin/../lib/libruby.so.2.6(sigsegv+0x42) [0x7f8350cab052] signal.c:998
/lib/x86_64-linux-gnu/libc.so.6(0x7f835071af20) [0x7f835071af20]
[0x7f835086a5a1]
/opt/ruby2.6.1/bin/../lib/libruby.so.2.6(rb_str_new_cstr+0xe) [0x7f8350cc309e] string.c:811
/u/apps/bc3/shared/bundle-ruby221/ruby/2.6.0/gems/bcrypt-3.1.13/lib/bcrypt_ext.so(bc_salt+0x6a) [0x7f833ec9f01a] bcrypt_ext.c:21