treeify: fix path canonicalization again
treeify: fix path canonicalization again

Previous fix broke many other inputs like `find foo bar | treeify`. Now
the output is actually more consistent with `tree`.

A downside is that one now needs to use `treeify ./foo` instead of just
`treeify foo` if the input has "./foo/.....".

grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks