[PATCH 2 of 2] histedit: add transaction for cleanup when obsmarkers are enabled

[Laurent Charignon]

# HG changeset patch
# User Laurent Charignon <lcharignon at fb.com>
# Date 1438026262 25200
#      Mon Jul 27 12:44:22 2015 -0700
# Branch stable
# Node ID 70b33c794a0d59186243378c6c492a7157c463c9
# Parent  1ce021437a02319df153e5e535c0ce9885160e89
histedit: add transaction for cleanup when obsmarkers are enabled

This patch adds transaction for the cleanup phase.
Before this patch, the histedit cleanup was creating markers on replaced nodes
first and then on temp nodes.
If we prune the replaced nodes first they will be obsolete but kept visible
until we prune the temp nodes. This is particularly concerning in the case of
inhibit where these nodes would be made visible outside of the duration of the
histedit command.
We should do both operations within one transaction to avoid this issue.
We don't open a transaction when createmarkers is not enabled as strip does
not work within transactions.

diff --git a/hgext/histedit.py b/hgext/histedit.py
--- a/hgext/histedit.py
+++ b/hgext/histedit.py
@@ -169,6 +169,7 @@ from mercurial import context
 from mercurial import exchange
 from mercurial import extensions
 from mercurial import hg
+from mercurial import lock as lockmod
 from mercurial import node
 from mercurial import repair
 from mercurial import scmutil
@@ -908,7 +909,16 @@ def _histedit(ui, repo, state, *freeargs
                     for n in succs[1:]:
                         ui.debug(m % node.short(n))
 
-    cleanup(ui, repo, state, mapping, ntm, supportsmarkers, tmpnodes)
+    lock, tr = None, None
+    try:
+        if supportsmarkers:
+            lock = repo.lock()
+            tr = repo.transaction("cleanup")
+        cleanup(ui, repo, state, mapping, ntm, supportsmarkers, tmpnodes)
+        if tr is not None:
+            tr.close()
+    finally:
+        lockmod.release(tr, lock)
 
 def bootstrapcontinue(ui, state, opts):
     repo = state.repo