rbenv-rehash + rbenv-gemsets produces a spurious shim

[telemachus]

I wasn't sure whether to post this bug here or on rbenv-gemsets, so I'm putting it here and cc-ing @jamis.

Once you have rbenv-gemsets installed, rehashing can produce a spurious file in shims called * (no joke). I can't even figure out a way to explain it briefly, so I'm just going to show how I found it:

1. At the top of make_shims in rbenv-rehash add echo "glob: $@"

2. Run rbenv rehash

3. Get this result:

   glob: ../versions/1.9.2-p290/bin/erb ../versions/1.9.2-p290/bin/gem ../versions/1.9.2-p290/bin/irb ../versions/1.9.2-p290/bin/rake ../versions/1.9.2-p290/bin/rdoc ../versions/1.9.2-p290/bin/ri ../versions/1.9.2-p290/bin/ruby ../versions/1.9.2-p290/bin/testrb
   
   glob: /Users/telemachus/.rbenv/versions/*/gemsets/*/bin/*
   

That second item gets truncated to *, a file of that name is created and then treated as a proper shim. At the moment, this isn't a huge deal, but it's worth considering now before the gemsets idea grows.

[jamis]

Yeah, this is an issue with rbenv-gemsets, not rbenv. The rehash/gemset.bash plugin should have shopt -s nullglob, so that it expands to nothing instead of the glob pattern when nothing matches. I thought I had that in there, honestly; I must have removed it during experimenting and forgot to add it back. I'll work on that tonight.