RF: Reimplement GitRepo.merge_base() without GitPython

[mih]

This furthers gh-2879

[mih]

Appveyor failure is only coverage submission.

[kyleam]

Thanks, looks good to me. I have only minor comments.

[kyleam]

bases made sense given the gitpython return value, but I think for clarity (because we don't support --all) the rewrite should use base.

[mih]

Will do.

[kyleam]

There's a change in behavior here, switching to logging unknown exceptions rather than raising them. My preference would be to raise the error rather than logging in this situation. Perhaps something like this:

diff --git a/datalad/support/gitrepo.py b/datalad/support/gitrepo.py
index 30f08f652..642bfb511 100644
--- a/datalad/support/gitrepo.py
+++ b/datalad/support/gitrepo.py
@@ -1979,12 +1979,12 @@ def get_merge_base(self, commitishes):
         try:
             bases = self.call_git_oneline(['merge-base'] + commitishes)
         except CommandError as exc:
-            if "fatal: Not a valid object name" not in exc.stderr and (
-                    exc.stdout or exc.stderr):
-                # we don't know what this is, and we have something to tell about it
-                # then log it. Without output, it could also just be "no merge base"
-                lgr.debug(exc_str(exc))
-            return None
+            if exc.code == 1 and not (exc.stdout or exc.stderr):
+                # No merge base was found (unrelated commits).
+                return None
+            if "fatal: Not a valid object name" in exc.stderr:
+                return None
+            raise
 
         if not bases:
             return None

I don't have a strong objection to leaving it as is, though.

[mih]

I like this more than what I did, will change. Thx!

[kyleam]

This condition isn't relevant any more, is it?

[mih]

True, will remove.

[codecov]

Codecov Report

Merging #4170 into master will decrease coverage by 0.22%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master    #4170      +/-   ##
==========================================
- Coverage   89.13%   88.91%   -0.23%     
==========================================
  Files         275      275              
  Lines       35847    35846       -1     
==========================================
- Hits        31953    31872      -81     
- Misses       3894     3974      +80

Impacted Files	Coverage Δ
datalad/support/gitrepo.py	90.28% <83.33%> (-0.37%)	⬇️
datalad/customremotes/base.py	69.25% <0%> (-14.89%)	⬇️
datalad/customremotes/tests/__init__.py	91.66% <0%> (-8.34%)	⬇️
datalad/support/keyring_.py	84.44% <0%> (-6.67%)	⬇️
datalad/tests/test_base.py	96.55% <0%> (-3.45%)	⬇️
datalad/customremotes/tests/test_archives.py	86.27% <0%> (-3.27%)	⬇️
datalad/downloaders/http.py	70.91% <0%> (-2.79%)	⬇️
datalad/downloaders/tests/test_http.py	58.39% <0%> (-2.19%)	⬇️
datalad/__init__.py	88.88% <0%> (-1.49%)	⬇️
datalad/cmd.py	91.91% <0%> (-1.28%)	⬇️
... and 8 more

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[mih]

A pushed the changes you pointed out @kyleam

[kyleam]

A pushed the changes you pointed out @kyleam

Thanks, LGTM