shrink-revlog: improve performance: use changegroup instead of revisions
Before:
real 0m23.971s
Now:
real 0m4.229s
The only case where the output would be different is if the newer hg was using
a different diff algorithm than used originally.
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
applying bad.patch
R link
? bad.patch