outgoing: merge the code handling --graph with the main one
The --graph code had its own copy of the logic. With the previous reorganisation
of the code, we can now merge it with the main code, reducing fragile
complication.
As a side effect, `hg out --graph` now use the right return code when they are
nothing outgoing. This explain the change to output in
`tests/test-largefiles-misc.t`.
Differential Revision: https://phab.mercurial-scm.org/D10383
$ cat >> $HGRCPATH << EOF
> [command-templates]
> log="{rev}:{node|short} ({phase}) [{tags} {bookmarks}] {desc|firstline}\n"
> [extensions]
> dirstateparanoidcheck = $TESTDIR/../contrib/dirstatenonnormalcheck.py
> [experimental]
> nonnormalparanoidcheck = True
> [devel]
> all-warnings=True
> EOF
$ mkcommit() {
> echo "$1" > "$1"
> hg add "$1"
> hg ci -m "add $1"
> }
$ hg init testrepo
$ cd testrepo
$ mkcommit a
$ mkcommit b
$ mkcommit c
$ hg status