bisect: allow resetting with unfinished graft/rebase/etc

"hg bisect --reset" just deletes the state file (it doesn't move back
to the starting point like rebase does); it can not conflict with an
ongoing rebase etc.

checkunfinished() has this documentation:

  It's probably good to check this right before bailifchanged().

So that's where I moved it.

mercurial/commands.py

@@ -837,8 +837,6 b' def bisect(ui, repo, rev=None, extra=Non'
     elif extra or good + bad + skip + reset + extend + bool(command) > 1:
         raise error.Abort(_('incompatible arguments'))
 
-    cmdutil.checkunfinished(repo)
-
     if reset:
         hbisect.resetstate(repo)
         return
@@ -865,6 +863,7 b' def bisect(ui, repo, rev=None, extra=Non'
         """common used update sequence"""
         if noupdate:
             return
+        cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
         return hg.clean(repo, node, show_stats=show_stats)
 

tests/test-bisect.t

@@ -551,7 +551,14 b' test the same case, this time with updat'
   date:        Thu Jan 01 00:00:06 1970 +0000
   summary:     msg 6
   
-
+  $ hg graft -q 15
+  warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
+  abort: unresolved conflicts, can't continue
+  (use 'hg resolve' and 'hg graft --continue')
+  [255]
+  $ hg bisect --reset
+  $ hg up -C .
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
 Check that bisect does not break on obsolete changesets
 =========================================================