Prune stale branches when fetching from remote

[benjamb]

Fixes occasional error where local refs conflict with changes on the
remote:

error: some local refs could not be updated; try running
'git remote prune origin' to remove any old, conflicting branches

[aschmolck]

Thanks for reporting the issue and sending an PR to fix it!

But I think instead of the more esoteric remote update --prune, we could just stick with fetch and add --prune, correct?

[benjamb]

Yep, correct. Unsure why I didn't just resort to that, probably because I tend to use git remote update --prune rather than fetch or pull myself. Force pushed an update, it now sticks with fetch.

[jcpetruzza]

Thanks for the fix!