bundle2: also save output when error happens during part processing

Until this changeset, we were only able to save output if an error happened
during the 'transaction.close()' phase. If the 'processbundle' call raised an
exception, the 'bundleoperation' object was never returned, so the reply bundle
was never accessible and no output could be salvaged. We introduce a quick (but
not very elegant) fix to gain access to any reply created during the processing.

This conclude this output related series. We should hopefully be able client-side to see the
whole server output, in a proper order.

The code is now complex enough that a refactoring of it would make sense on
default.

mercurial/bundle2.py

@@ -285,7 +285,7 b' def _notransaction():'
     to be created"""
     raise TransactionUnavailable()
 
-def processbundle(repo, unbundler, transactiongetter=None):
+def processbundle(repo, unbundler, transactiongetter=None, op=None):
     """This function process a bundle, apply effect to/from a repo
 
     It iterates over each part then searches for and uses the proper handling
@@ -295,7 +295,13 b' def processbundle(repo, unbundler, trans'
     before final usage.
 
     Unknown Mandatory part will abort the process.
+
+    It is temporarily possible to provide a prebuilt bundleoperation to the
+    function. This is used to ensure output is properly propagated in case of
+    an error during the unbundling. This output capturing part will likely be
+    reworked and this ability will probably go away in the process.
     """
+    if op is None:
     if transactiongetter is None:
         transactiongetter = _notransaction
     op = bundleoperation(repo, transactiongetter)

mercurial/exchange.py

@@ -1297,7 +1297,11 b' def unbundle(repo, cg, heads, source, ur'
                 tr.hookargs['source'] = source
                 tr.hookargs['url'] = url
                 tr.hookargs['bundle2'] = '1'
-                r = bundle2.processbundle(repo, cg, lambda: tr).reply
+                op = bundle2.bundleoperation(repo, lambda: tr)
+                try:
+                    r = bundle2.processbundle(repo, cg, op=op)
+                finally:
+                    r = op.reply
                 if r is not None:
                     repo.ui.pushbuffer(error=True, subproc=True)
                     def recordout(output):

tests/test-bundle2-exchange.t

@@ -619,3 +619,51 b' Doing the actual push: hook abort'
   $ ls -1 other/.hg/store/00changelog.i*
   other/.hg/store/00changelog.i
 
+Check error from hook during the unbundling process itself
+
+  $ cat << EOF >> $HGRCPATH
+  > pretxnchangegroup = echo "Fail early!"; false
+  > EOF
+  $ "$TESTDIR/killdaemons.py" $DAEMON_PIDS # reload http config
+  $ hg -R other serve -p $HGPORT2 -d --pid-file=other.pid -E other-error.log
+  $ cat other.pid >> $DAEMON_PIDS
+
+  $ hg -R main push other -r e7ec4e813ba6
+  pushing to other
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: Fail early!
+  remote: transaction abort!
+  remote: Cleaning up the mess...
+  remote: rollback completed
+  abort: pretxnchangegroup hook exited with status 1
+  [255]
+  $ hg -R main push ssh://user@dummy/other -r e7ec4e813ba6
+  pushing to ssh://user@dummy/other
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: Fail early!
+  remote: transaction abort!
+  remote: Cleaning up the mess...
+  remote: rollback completed
+  abort: pretxnchangegroup hook exited with status 1
+  [255]
+  $ hg -R main push http://localhost:$HGPORT2/ -r e7ec4e813ba6
+  pushing to http://localhost:$HGPORT2/
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: Fail early!
+  remote: transaction abort!
+  remote: Cleaning up the mess...
+  remote: rollback completed
+  abort: pretxnchangegroup hook exited with status 1
+  [255]