phabricator: do not upload new diff if nothing changes...
phabricator: do not upload new diff if nothing changes
Previously, `phabsend` uploads new diffs as long as the commit hash changes.
That's suboptimal because sometimes the diff is exactly the same as before,
the commit hash change is caused by a parent hash change, or commit message
change which do not affect diff content.
This patch adds a check examining actual diff contents to skip uploading new
diffs in that case.