Support for the Ruby 2.4 series has ended. See here for reference.
A GitSpecification represents a gem that is sourced from a git repository and is being loaded through a gem dependencies file through the git: option.
Installing a git gem only involves building the extensions and generating the executables.
# File rubygems/resolver/git_specification.rb, line 24
def install options = {}
require 'rubygems/installer'
installer = Gem::Installer.for_spec spec, options
yield installer if block_given?
installer.run_pre_install_hooks
installer.build_extensions
installer.run_post_build_hooks
installer.generate_bin
installer.run_post_install_hooks
end