histedit: create transaction outside of try

Just a little refactoring to simplify the next patch.

Differential Revision: https://phab.mercurial-scm.org/D65

hgext/histedit.py

@@ -1107,14 +1107,13 def _continuehistedit(ui, repo, state):
         if action.verb == 'fold' and nextact and nextact.verb == 'fold':
             state.actions[idx].__class__ = _multifold
 
+    # Force an initial state file write, so the user can run --abort/continue
+    # even if there's an exception before the first transaction serialize.
+    state.write()
+
     total = len(state.actions)
     pos = 0
     tr = None
-
-    # Force an initial state file write, so the user can run --abort/continue
-    # even if there's an exception before the first transaction serialize.
-    state.write()
-    try:
         # Don't use singletransaction by default since it rolls the entire
         # transaction back if an unexpected exception happens (like a
         # pretxncommit hook throws, or the user aborts the commit msg editor).
@@ -1123,7 +1122,7 def _continuehistedit(ui, repo, state):
             # and reopen a transaction. For example, if the action executes an
             # external process it may choose to commit the transaction first.
             tr = repo.transaction('histedit')
-
+    try:
         while state.actions:
             state.write(tr=tr)
             actobj = state.actions[0]