Add a way to specify a particular commit in URLs
Add a way to specify a particular commit in URLs

Since the HEAD of a repo may be where development happens and a
particular tag or commit will correspond to a particular version of a
module, allow URLS of the form  git://github.com/foo/bar@v1.2.3
to checkout the commit specified by "v1.2.3" once the repo is cloned.

timo/panda,niner/panda,raydiak/panda,shoichikaji/panda,TimToady/panda,cygx/panda,hoelzro/panda,hoelzro/panda,stmuk/panda,TimToady/panda,tadzik/panda,tadzik/panda,cygx/panda,moznion/panda,shoichikaji/panda,will-crawford/panda,will-crawford/panda,skaji/panda,perlpilot/panda,masak/panda,niner/panda,sjn/panda,jonathanstowe/panda,skaji/panda,raydiak/panda,nbrown/panda,laben/panda,stmuk/panda,nbrown/panda,tadzik/panda,masak/panda,hoelzro/panda,moznion/panda,sjn/panda,laben/panda,sjn/panda,perlpilot/panda,timo/panda,jonathanstowe/panda