add ability to read symlink basedirs

[klnusbaum]

Imagine the following scenario: A user has a Go project. This directory is sitting in an arbitrary location in their file system and the user would like to keep it there. However, they need it to work with Go tooling, so they symlink it into an appropriate location in their GOPATH, e.g. $GOPATH/src/github.com/user1/myproject. The user then decides they's like to start using glide, so they cd to $GOPATH/src/github.com/user1/myproject and run glide create to generate their initial glide.yaml file. The result is the creation of empty glide.yaml file. Sad times.

What's happening is that the basedir given to NewResolver is actually a symlink. This in turn causes an issue in the ResolveLocal function. The if !fi.IsDir() check fails since the basedir isn't actually a directory, it's a symlink.

Let's add a check to the NewResolver function. After getting the absolute path of the provided basedir, let's check to see if it's a symlink. If it is, read the symlink and use that as the basedir instead. If not, proceed as normal.

[mattfarina]

I really like this change.

Unfortunately, I case where project can be added to itself. For example,

package: github.com/foo/bar
import:
- package: github.com/foo/bar
  subpackages:
  - baz
  - qux

I discovered this on a private project so I can't share.

Once we get this fixed I'll be happy to merge this. I'll try to dig into it more later this week. If you find the solution before then that would be great, too.

Note, updated to fix formatting.

[klnusbaum]

Hey @mattfarina, any updates on this?

[mattfarina]

@klnusbaum I've been traveling and then had a holiday weekend so I got a little behind. Need to figure out that bug so we can merge this.

[mattfarina]

@klnusbaum I found the problem, fixed it, and merged into master. Thanks for the contribution.

[klnusbaum]

awsome! Thanks @mattfarina !