dirstate: show develwarn for write() invocation without transaction

This is used to detect 'dirstate.write()' invocation without the value
gotten by 'repo.currenttransaction()' (mainly focused on 3rd party
extensions).

hgext/largefiles/lfutil.py

@@ -110,6 +110,11 b' class largefilesdirstate(dirstate.dirsta'
         return super(largefilesdirstate, self).normallookup(unixpath(f))
     def _ignore(self, f):
         return False
+    def write(self, tr=False):
+        # (1) disable PENDING mode always
+        #     (lfdirstate isn't yet managed as a part of the transaction)
+        # (2) avoid develwarn 'use dirstate.write with ....'
+        super(largefilesdirstate, self).write(None)
 
 def openlfdirstate(ui, repo, create=True):
     '''

mercurial/dirstate.py

@@ -661,6 +661,11 b' class dirstate(object):'
 
         filename = self._filename
         if tr is False: # not explicitly specified
+            if (self._ui.configbool('devel', 'all-warnings')
+                or self.ui.configbool('devel', 'check-dirstate-write')):
+                self._ui.develwarn('use dirstate.write with '
+                                   'repo.currenttransaction()')
+
             if self._opener.lexists(self._pendingfilename):
                 # if pending file already exists, in-memory changes
                 # should be written into it, because it has priority