Avoid excess commits to the git-annex branch when stall detection is enabled

When git-annex transferrer started up, and the journal contained something,
it would commit it to the git-annex branch. This caused excess commits to
the branch, in cases where normally several changes would be journalled and
committed together. That generated some excess git objects and was also
just noisy on stdout.

Since transferrer uses enableInteractiveBranchAccess, it does not need to
commit journalled changes, since the optimisation that avoids checking
the journal when reading from the branch is disabled for processes that
call that.

This commit was sponsored by Svenne Krap on Patreon.

Annex/BranchState.hs

@@ -37,18 +37,21 @@ checkIndexOnce a = unlessM (indexChecked <$> getState) $ do
  - before got staged (or if the journal was empty). That lets an opmisation
  - be done: The journal then does not need to be checked going forward,
  - until new information gets written to it.
+ -
+ - When interactive access is enabled, the journal is always checked when
+ - reading values from the branch, and so this does not need to update
+ - the branch.
  -}
 runUpdateOnce :: Annex Bool -> Annex BranchState
 runUpdateOnce a = do
 	st <- getState
-	if branchUpdated st
+	if branchUpdated st || needInteractiveAccess st
 		then return st
 		else do
 			journalstaged <- a
 			let stf = \st' -> st'
 				{ branchUpdated = True
 				, journalIgnorable = journalstaged 
-					&& not (needInteractiveAccess st')
 				}
 			changeState stf
 			return (stf st)

CHANGELOG

@@ -1,6 +1,8 @@
 git-annex (8.20210331) UNRELEASED; urgency=medium
 
   * Fix build with persistent-2.12.0.1
+  * Avoid excess commits to the git-annex branch when stall detection is
+    enabled.
 
  -- Joey Hess <id@joeyh.name>  Thu, 01 Apr 2021 12:17:26 -0400