evolve doesn't load in some hggit clone

[Ernie Rael]

With Win7,mercurial-5.6 (from python3 64.msi, not Tortoisehg)

A python3 problem?

Failure to load evolve if in a recently used git repository.
In an older repo (cloned from same git repo), or no repo,
or clone not hg-git then it finds evolve.

If I use Tortoisehg 5.6 (Python27), things work as expected.

I'm happy to provide more info, and I don't know where to start...

Where it works hg debugconfig shows
 Â Â Â  extensions.hggit=C:/f/pf/Python38/lib/site-packages/hggit
extensions.evolve=C:/f/pf/Python38/lib/site-packages/hgext3rd/evolve
extensions.topic=C:/f/pf/Python38/lib/site-packages/hgext3rd/topic
And where it doesn't
 Â Â Â  extensions.hggit=C:/f/pf/Python38/lib/site-packages/hggit
extensions.topic=C:/f/pf/Python38/lib/site-packages/hgext3rd/topic


=== In a directory which is not a repo
$ hg --version -v
Mercurial Distributed SCM (version 5.6)
   evolve      external  10.1.0
   hggit       external  0.9.0 (dulwich 0.20.11)
   topic       external  0.20.0


=== In a recently used git clone repo, note evolve does not load

/f/repos/swingset/swingset-4
$ hg --version
*** failed to import extension evolve: No module named 'evolve'
Mercurial Distributed SCM (version 5.6)

=== In an older git clone repo, not used for a while

/f/repos/swingset/swingset-code
$ hg --version
Mercurial Distributed SCM (version 5.6)