Having issues compiling on the lastest version of Debian 9

In omnibus we are getting this error:

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/allocations-1.0.5/ext/liballocations
/opt/gitlab/embedded/bin/ruby -r ./siteconf20170918-20001-15apnjz.rb extconf.rb
creating Makefile

current directory:
/opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/allocations-1.0.5/ext/liballocations
make "DESTDIR=" clean

current directory:
/opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/allocations-1.0.5/ext/liballocations
make "DESTDIR="
compiling liballocations.c
In file included from /opt/gitlab/embedded/include/ruby-2.3.0/ruby.h:33:0,
                 from liballocations.h:4,
                 from liballocations.c:1:
/opt/gitlab/embedded/include/ruby-2.3.0/ruby/ruby.h:837:45: warning: enumerator
value for ‘RUBY_FL_USER19’ is not an integer constant expression [-Wpedantic]
 #define RUBY_FL_USER_N(n) RUBY_FL_USER##n = (1<<(RUBY_FL_USHIFT+n))
                                             ^
/opt/gitlab/embedded/include/ruby-2.3.0/ruby/ruby.h:858:5: note: in expansion of
macro ‘RUBY_FL_USER_N’
     RUBY_FL_USER_N(19),
     ^~~~~~~~~~~~~~
compiling state.c
In file included from /opt/gitlab/embedded/include/ruby-2.3.0/ruby.h:33:0,
                 from liballocations.h:4,
                 from state.h:4,
                 from state.c:1:
/opt/gitlab/embedded/include/ruby-2.3.0/ruby/ruby.h:837:45: warning: enumerator
value for ‘RUBY_FL_USER19’ is not an integer constant expression [-Wpedantic]
 #define RUBY_FL_USER_N(n) RUBY_FL_USER##n = (1<<(RUBY_FL_USHIFT+n))
                                             ^
/opt/gitlab/embedded/include/ruby-2.3.0/ruby/ruby.h:858:5: note: in expansion of
macro ‘RUBY_FL_USER_N’
     RUBY_FL_USER_N(19),
     ^~~~~~~~~~~~~~
linking shared-object liballocations.so

current directory:
/opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/allocations-1.0.5/ext/liballocations
make "DESTDIR=" install
make: /usr/bin/mkdir: Command not found
Makefile:196: recipe for target '.RUBYARCHDIR.time' failed
make: *** [.RUBYARCHDIR.time] Error 127

make install failed, exit code 2

https://dev.gitlab.org/gitlab/omnibus-gitlab/-/jobs/1435718

This is on a fresh debian 9 docker image, with ruby 2.3.5

An older debian 9 with ruby 2.3.3 continues to work fine

cc\ @yorickpeterse