module_name linking creates invalid links in some cases

[jbedard]

Will try to collect and provide more info, but I think at minimum there's issues when. A lot of these cases overlap though:

Inconsistent sibling mappings (one name/dir different):

@foo/bar/a => /path/x
@foo/bar/b => /path/b
@foo/bar/c => /path/c

Inconsistent siblings mappings (one path having an extra entry):

@foo/bar/a => /path/x/a
@foo/bar/b => /path/b
@foo/bar/c => /path/c

Parent having an extra mapping:

@foo/bar => /path/other/lib
@foo/bar/a => /path/lib/a
@foo/bar/b => /path/lib/b
@foo/bar/c => /path/lib/c

Siblings with different link types:

@foo/bar/a => /path/lib/a (bin)
@foo/bar/b => /path/lib/b (src)
@foo/bar/c => /path/lib/c (bin)

Parent with different link type:

@foo/bar => /path/lib (src)
@foo/bar/a => /path/lib/a (bin)
@foo/bar/b => /path/lib/b (bin)
@foo/bar/c => /path/lib/c (bin)