rails/rails — pull request #17640 by michaeljayt (2014-11-16 18:49:47+00:00)
Title: Skip spring install in Cygwin due to fork() bad support.

Process.respond_to?(:fork) returns true in Cygwin, but due to platform difference, spring will failed to work as expected in Unix-like systems.

See also: https://www.cygwin.com/faq.html#faq.using.fixing-fork-failures