Add git fetch.
Add git fetch command.
Cleanup git pull.
more cleanup and nits.
Rename sha => shaBytes in PackedObject.
Make sha public in GitObject.
Support fast-forward merges.
remove unused functions in git pull.
Add LowestCommonAncestor for commits.
Dont throw error if a commit is not found locally.
Fix bug in getCommitGraph, getCommonAncestor.
Switch back to shallow clone.
Handle case of only localHead modified.
More work on git merge.
Addressed comments.
Add placeholder for fetch_test.
Merge pull request #959 from dart-lang/git_fetch2

Support fast forward git merge.