transplant: widen wlock scope of transplant for consitency while processing

transplant: widen wlock scope of transplant for consitency while processing

Before this patch, "hg transplant" executes below before acquisition
of wlock.

  - cmdutil.checkunfinished()
  - repo.status() for dirty check
  - repo.dirstate.parents()

It may cause unintentional result, if another command runs parallelly
(see also issue4368).

This patch makes "hg transplant" acquire wlock before processing
instead of acquiring wlock in each of 'transplanter.apply()' and
'transplanter.recover()'.

--- a/hgext/transplant.py	Wed Dec 09 08:28:53 2015 +0900
+++ b/hgext/transplant.py	Wed Dec 09 08:28:53 2015 +0900
@@ -20,6 +20,7 @@
 from mercurial import bundlerepo, hg, merge, match
 from mercurial import patch, revlog, scmutil, util, error, cmdutil
 from mercurial import revset, templatekw, exchange
+from mercurial import lock as lockmod
 
 class TransplantError(error.Abort):
     pass
@@ -127,9 +128,8 @@
         diffopts = patch.difffeatureopts(self.ui, opts)
         diffopts.git = True
 
-        lock = wlock = tr = None
+        lock = tr = None
         try:
-            wlock = repo.wlock()
             lock = repo.lock()
             tr = repo.transaction('transplant')
             for rev in revs:
@@ -224,7 +224,6 @@
                 tr.release()
             if lock:
                 lock.release()
-            wlock.release()
 
     def filter(self, filter, node, changelog, patchfile):
         '''arbitrarily rewrite changeset before applying it'''
@@ -345,7 +344,6 @@
                 merge = True
 
         extra = {'transplant_source': node}
-        wlock = repo.wlock()
         try:
             p1, p2 = repo.dirstate.parents()
             if p1 != parent:
@@ -367,7 +365,9 @@
 
             return n, node
         finally:
-            wlock.release()
+            # TODO: get rid of this meaningless try/finally enclosing.
+            # this is kept only to reduce changes in a patch.
+            pass
 
     def readseries(self):
         nodes = []
@@ -572,6 +572,14 @@
     and then resume where you left off by calling :hg:`transplant
     --continue/-c`.
     '''
+    wlock = None
+    try:
+        wlock = repo.wlock()
+        return _dotransplant(ui, repo, *revs, **opts)
+    finally:
+        lockmod.release(wlock)
+
+def _dotransplant(ui, repo, *revs, **opts):
     def incwalk(repo, csets, match=util.always):
         for node in csets:
             if match(node):