withAltRepo needs a separate queue of changes

The queue could potentially contain changes from before withAltRepo, and
get flushed inside the call, which would apply the changes to the modified
repo.

Or, changes could be queued in withAltRepo that were intended to affect
the modified repo, but don't get flushed until later.

I don't know of any cases where either happens, but better safe than sorry.

Note that this affect withIndexFile, which is used in git-annex branch
updates. So, it potentially makes things slower. Should not be by much;
the overhead consists only of querying the current queue a couple of times,
and potentially flushing changes queued within withAltRepo earlier, that
could have maybe been bundled with other later changes.

Notice in particular that the existing queue is not flushed when calling
withAltRepo. So eg when git annex add needs to stage files in the index,
it will still bundle them together efficiently.

1 files changed, 1 insertions, 0 deletions

diff --git a/Annex/Queue.hs b/Annex/Queue.hs
index 0e1b0f68c..9c22e75fd 100644
--- a/Annex/Queue.hs
+++ b/Annex/Queue.hs
@@ -13,6 +13,7 @@ module Annex.Queue (
 	flush,
 	flushWhenFull,
 	size,
+	get,
 	mergeFrom,
 ) where