The local source finds gems in the current directory for fulfilling dependencies.
Local
sorts before Gem::Source
and after Gem::Source::Installed
# File rubygems/source/local.rb, line 18 def <=> other case other when Gem::Source::Installed, Gem::Source::Lock then -1 when Gem::Source::Local then 0 when Gem::Source then 1 else nil end end