revlog-split: show manifest data loss situation when using clonebundle

After the commit of the transaction from applying the clone bundle, changes to
the manifest from the subsequent pull would write index data in the wrong file.
This lead to data being "lost" after the pull and the repository to be
corrupted. We add a test checking this specific scenario.

In practice, the issue only affects the manifest but we also test the issue with a file for future proofing things up.

See test documentation and failure for details.

tests/test-clonebundles.t

@@ -638,3 +638,120 b' on a 32MB system.'
   updating the branch cache
   (sent 4 HTTP requests and * bytes; received * bytes in responses) (glob)
   $ killdaemons.py
+
+Testing a clone bundles that involves revlog splitting (issue6811)
+==================================================================
+
+  $ cat >> $HGRCPATH << EOF
+  > [format]
+  > revlog-compression=none
+  > use-persistent-nodemap=no
+  > EOF
+
+  $ hg init server-revlog-split/
+  $ cd server-revlog-split
+  $ cat >> .hg/hgrc << EOF
+  > [extensions]
+  > clonebundles =
+  > EOF
+  $ echo foo > A
+  $ hg add A
+  $ hg commit -m 'initial commit'
+IMPORTANT: the revlogs must not be split
+  $ ls -1 .hg/store/00manifest.*
+  .hg/store/00manifest.i
+  $ ls -1 .hg/store/data/_a.*
+  .hg/store/data/_a.i
+
+do big enough update to split the revlogs
+
+  $ $TESTDIR/seq.py 100000 > A
+  $ mkdir foo
+  $ cd foo
+  $ touch `$TESTDIR/seq.py 10000`
+  $ cd ..
+  $ hg add -q foo
+  $ hg commit -m 'split the manifest and one filelog'
+
+IMPORTANT: now the revlogs must be split
+  $ ls -1 .hg/store/00manifest.*
+  .hg/store/00manifest.d
+  .hg/store/00manifest.i
+  $ ls -1 .hg/store/data/_a.*
+  .hg/store/data/_a.d
+  .hg/store/data/_a.i
+
+Add an extra commit on top of that
+
+  $ echo foo >> A
+  $ hg commit -m 'one extra commit'
+
+  $ cd ..
+
+Do a bundle that contains the split, but not the update
+
+  $ hg bundle --exact --rev '::(default~1)' -R server-revlog-split/ --type gzip-v2 split-test.hg
+  2 changesets found
+
+  $ cat > server-revlog-split/.hg/clonebundles.manifest << EOF
+  > http://localhost:$HGPORT1/split-test.hg BUNDLESPEC=gzip-v2
+  > EOF
+
+start the necessary server
+
+  $ "$PYTHON" $TESTDIR/dumbhttp.py -p $HGPORT1 --pid http.pid
+  $ cat http.pid >> $DAEMON_PIDS
+  $ hg -R server-revlog-split serve -d -p $HGPORT --pid-file hg.pid --accesslog access.log
+  $ cat hg.pid >> $DAEMON_PIDS
+
+Check that clone works fine
+===========================
+
+Here, the initial clone will trigger a revlog split (which is a bit clowny it
+itself, but whatever). The split revlogs will see additionnal data added to
+them in the subsequent pull. This should not be a problem
+
+  $ hg clone http://localhost:$HGPORT revlog-split-in-the-bundle
+  applying clone bundle from http://localhost:$HGPORT1/split-test.hg
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 10002 changes to 10001 files
+  finished applying clone bundle
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  new changesets e3879eaa1db7
+  2 local changesets published
+  updating to branch default
+  10001 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+check the results
+
+  $ cd revlog-split-in-the-bundle
+  $ f --size .hg/store/00manifest.*
+  .hg/store/00manifest.d: size=499037
+  .hg/store/00manifest.i: size=192 (missing-correct-output !)
+  .hg/store/00manifest.i: size=128 (known-bad-output !)
+  .hg/store/00manifest.i.s: size=64 (known-bad-output !)
+  $ f --size .hg/store/data/_a.*
+  .hg/store/data/_a.d: size=588917
+  .hg/store/data/_a.i: size=192
+
+manifest should work
+
+  $ hg  files -r tip | wc -l
+  \s*10001 (re) (missing-correct-output !)
+  abort: 00manifest@4941afd6b8e298d932227572c5c303cbc14301bd: no node (known-bad-output !)
+  0 (known-bad-output !)
+
+file content should work
+
+  $ hg  cat -r tip A | wc -l
+  \s*100001 (re) (missing-correct-output !)
+  abort: 00manifest@4941afd6b8e298d932227572c5c303cbc14301bd: no node (known-bad-output !)
+  0 (known-bad-output !)
+
+