upgrade: When upgrade fails due to an exception, display it.

37b42e72e7 made it catch exceptions but
thought they were unlikely to be useful to display, which may be right when
a git command fails, but not in the case yoh found.

CHANGELOG

@@ -9,6 +9,7 @@ git-annex (8.20200502) UNRELEASED; urgency=medium
   * repair: Improve fetching from a remote with an url in host:path format.
   * sync: Avoid an ugly error message when nothing has been committed to
     master yet and there is a synced master branch to merge from.
+  * upgrade: When upgrade fails due to an exception, display it.
 
  -- Joey Hess <id@joeyh.name>  Mon, 04 May 2020 12:46:11 -0400
 

Upgrade/V5.hs

@@ -36,7 +36,7 @@ import Annex.AdjustedBranch
 import qualified Data.ByteString as S
 
 upgrade :: Bool -> Annex Bool
-upgrade automatic = flip catchNonAsync (const $ return False) $ do
+upgrade automatic = flip catchNonAsync onexception $ do
 	unless automatic $
 		showAction "v5 to v6"
 	ifM isDirect
@@ -55,6 +55,10 @@ upgrade automatic = flip catchNonAsync (const $ return False) $ do
 	unlessM isDirect $
 		createInodeSentinalFile True
 	return True
+  where
+	onexception e = do
+		warning $ "caught exception: " ++ show e
+		return False
 
 -- git before 2.22 would OOM running git status on a large file.
 --

doc/bugs/upgrade___40__from_v5__41___fails_without_stating_any_reason__47__hints.mdwn

@@ -150,4 +150,4 @@ So it seems git-annex should revert back to reporting errors from underlying `gi
 [[!meta author=yoh]]
 [[!tag projects/datalad]]
 
-
+> [[fixed|done]], thanks for tracking it back to the root cause. --[[Joey]]