This allows godoc.org to work on nested packages. As it stood gddo would
fail trying to find nested packages. Let's say we have a vaind with this
route:
go.mcquay.me/vain -> https://s.mcquay.me/sm/vain
Asking godoc for go.mcquay.me/vain would work fine. However trying to
get documentation for go.mcquay.me/vain/errors (nested package) would
return 404 since it wouldn't match known paths exactly.
Since now we match and return "go.mcquay.me/vain" for the full path,
gddo is able to use local caches for its information.
Change-Id: I599a75898493734fc652e507f477c11b1b1b13e8
the go tool currenty has a pathology where it mistakingly claims it
can't clone a repo because it checks prefix by bytes, not by splitting
the path on slash.
Once https://github.com/golang/go/issues/15947 comes out (go1.8) then go
tools will be able to handle being provided with valid but overlapping
packages.
For now though we'll just return meta for the requested package.
Change-Id: Ie5026e7d5c1377ff7d2c2140b21f9b745af69764
