exchange: expand usage of getchangegroupraw
The 'getchangegroupraw' is very simple (two lines) so we inline it in its only
caller. This exposes the 'outgoing' object of the part generator function, allowing
us to add information on the number of changesets contained in the part in a
later changeset. Such information is useful for progress bar.
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown