This looks good, but we need an email address in the username - can you add one and re-upload the change?

Thanks! This needed some tweaking on the commit message to line up with our format (which is checked by the test suite, but I've edited in-flight and am pushing now.)

It looks superficially correct - I didn't give it a detailed
inspection, but I trust you and Valentin on this.

Fails tests, eg:

--- tests/test-push-checkheads-unpushed-D7.t
+++ tests/test-push-checkheads-unpushed-D7.t.err
@@ -65,27 +65,16 @@
   $ mkcommit C0
   created new head
   $ hg debugobsolete `getid "desc(A0)"` `getid "desc(A1)"`
-  1 new obsolescence markers
-  obsoleted 1 changesets
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
   $ hg debugobsolete `getid "desc(A1)"` `getid "desc(A2)"`
-  1 new obsolescence markers
-  obsoleted 1 changesets
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
   $ hg debugobsolete --record-parents `getid "desc(A2)"`
-  1 new obsolescence markers
-  obsoleted 1 changesets
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
   $ hg log -G --hidden
-  @  0f88766e02d6 (draft): C0
-  |
-  | x  c1f8d089020f (draft): A2
-  |/
-  | x  ba93660aff8d (draft): A1
-  | |
-  | o  74ff5441d343 (draft): B0
-  |/
-  | x  8aaa48160adc (draft): A0
-  |/
-  o  1e4be0697311 (public): root
-
+  abort: cannot import name 'noderev' from 'mercurial.node' (/tmp/hgtests.5j0okzgk/install/lib/python/mercurial/node.py)
+  [255]

I hate to be That Guy but can you replace "simplify" in all these with some boilerplate about "compare revs and not ids because $REASON"? otherwise some enthusiastic architecture astronaut (probably me) is going to come back in the not-too-distant future and make it more generic and phrase things in terms of nodes rather than IDs.

So, I've gone through several of these now, and I realize: why are we moving towards revs and away from nodes? That's the opposite of the refactor I'd expect...

Landing this chain, but it'd be good to see some documentation for it show up soon.

Needs rebased.

Fair enough. This is ready, but needs rebased.

I'm sorry to report this needs rebased

(marking as request changes in that case)

I suspect this test works without network if setuptools is already installed, but I don't care enough to block it on that pedantry.

AFAICT this should be fine, but I'll give Yuya a while to catch problems.

I'm still confused here.

This still requires changes to resolve my comments.

I'm not happy about this footgun option, but see why we need it.

I'm honestly baffled, and don't really have time to take a look. Probably back this and its child out, and we'll roll it forward again after we drop py2?

Do you think we should go ahead and apply the local patch then until we can update the vendored copy?

Should we add a test that, if git-fast-import is available, actually tries the import and verifies that things look reasonable?

Yes, please remove the python-zstandard changes from here, and send them directly to @indygreg upstream for that.

I'm fine with this as-is, but I am sympathetic to the concern that the -- looks like a mistake. If we want to change it we can, since we've got a full release cycle ahead of us before this is binding.

Ping someone else please - I'm busy with other things this week. :(