Modules with undef versions result in warnings from internals

[haarg]

If a module that is being checked has no version, warnings will be issued:

Use of uninitialized value $installed in string le at /Users/gknop/perl5/libs/5.022000-darwin-2level/lib/perl5/Dist/CheckConflicts.pm line 190.
Use of uninitialized value in concatenation (.) or string at /Users/gknop/perl5/libs/5.022000-darwin-2level/lib/perl5/Dist/CheckConflicts.pm line 159.

In my case, this is happening because it's trying loading the wrong module due to a case insensitive filesystem. So loading the module succeeds, but it's actually populating a different package, leaving the expected package with no version.