packaging: update dulwich to drop the certifi dependency on Windows
The presence of `certifi` causes the system certificate store to be ignored,
which was reported as a bug against TortoiseHg[1]. It was only pulled in on
Windows because of `dulwich`, which was copied from the old TortoiseHg install
scripts, in order to support `hg-git`.
This version of `dulwich` raises the minimum `urllib3` to a version (1.25) that
does certificate verification by default, without the help of `certifi`[2]. We
already bundle a newer version of `urllib3`. Note that `certifi` can still be
imported from the user site directory, if installed there. But the installer no
longer disables the system certificates by default.
[1] https://foss.heptapod.net/mercurial/tortoisehg/thg/-/issues/5825
[2] https://github.com/jelmer/dulwich/issues/1025
Test null revisions (node 0000000000000000000000000000000000000000, aka rev -1)
in various circumstances.
Make an empty repo:
$ hg init a
$ cd a
$ hg files -r 0000000000000000000000000000000000000000
[1]
$ hg files -r .
[1]
Add an empty commit (this makes the changelog refer to a null manifest node):
$ hg commit -m "init" --config ui.allowemptycommit=true
$ hg files -r .
[1]
Strip that empty commit (this makes the changelog file empty, as opposed to missing):
$ hg --config 'extensions.strip=' strip . > /dev/null
$ hg files -r .
[1]