localrepo: refactor prepush logic
Simplifies the prepush check logic and makes it a lot more direct and
comprehensible. Instead of comparing the total local vs. remote head count, it
compares the number of new vs. removed heads.
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved