
This fixes the bug introduced by 8686b98612dc which broke bundlerEnv exprs when gemdir was a string (thus making gemset a string by `gemset = gemdir + "/gemset.nix"`) which made it being treated as a set.
This fixes the bug introduced by 8686b98612dc which broke bundlerEnv exprs when gemdir was a string (thus making gemset a string by `gemset = gemdir + "/gemset.nix"`) which made it being treated as a set.