interrupting fetch causes invalid state

[jmhodges]

If you hit Ctrl-C during one of the recursive dependency fetches of, say, gvt fetch github.com/spf13/hugo, the hugo dependency will be added to the manifest, but not all of the the dependencies required to do so will be. Then, when you go to run gvt fetch github.com/spf13/hugo again, you'll get an error about it already being in the manifest.

It'd be nice if interrupting a fetch didn't cause this kind of invalid state to occur, and instead only updated the manifest with what had been successfully downloaded.

[FiloSottile]

Thanks, this is a good point. I think it's also related to the fact that if you edit the manifest manually or use update (pre-#38) you might end up with missing dependencies, and there's no command to get you out of there.