phases: avoid a potentially costly dictionary interation in some case
If we retract for the draft phase, there is not non-public item to be retracted
and we can skip this part. This part is was apparently super costly thanks to
Python.
On mozilla-try-2019-02-18, a perf::unbundle call with a 10 000 changesets
bundle gives give use the following timing.
e57d4b868a3e: 4.6 seconds
ac1c75188440: 102.5 seconds
this-changeset: 30.0 seconds
So we recovered about ⅔ of the regression, the next changeset will give us the
rest back.
$ hg init a
$ cd a
$ echo 123 > a
$ hg add a
$ hg commit -m "a" -u a
$ cd ..
$ hg init b
$ cd b
$ echo 321 > b
$ hg add b
$ hg commit -m "b" -u b
$ hg pull ../a
pulling from ../a
searching for changes
abort: repository is unrelated
[255]
$ hg pull -f ../a
pulling from ../a
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 9a79c33a9db3
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg heads
changeset: 1:9a79c33a9db3
tag: tip
parent: -1:000000000000
user: a
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
changeset: 0:01f8062b2de5
user: b
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ cd ..