absorb: aborting if another operation is in progress

This increases safety of using absorb by both aborting when another operation
is in progress (since the absorption could confuse any other command a lot)
and holding the locks throughout the reading of the working directory (for
which changes to absorb) and the reading of the repo (for which changes to
absorb into).

Differential Revision: https://phab.mercurial-scm.org/D6237

tests/test-absorb-unfinished.t

@@ -0,0 +1,30 b''
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > absorb=
+  > EOF
+
+Abort absorb if there is an unfinished operation.
+
+  $ hg init abortunresolved
+  $ cd abortunresolved
+
+  $ echo "foo1" > foo.whole
+  $ hg commit -Aqm "foo 1"
+
+  $ hg update null
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo "foo2" > foo.whole
+  $ hg commit -Aqm "foo 2"
+
+  $ hg --config extensions.rebase= rebase -r 1 -d 0
+  rebasing 1:c3b6dc0e177a "foo 2" (tip)
+  merging foo.whole
+  warning: conflicts while merging foo.whole! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]
+
+  $ hg --config extensions.rebase= absorb
+  abort: rebase in progress
+  (use 'hg rebase --continue' or 'hg rebase --abort')
+  [255]
+

hgext/absorb.py

@@ -682,7 +682,6 b' class fixupstate(object):'
 
     def commit(self):
         """commit changes. update self.finalnode, self.replacemap"""
-        with self.repo.wlock(), self.repo.lock():
             with self.repo.transaction('absorb') as tr:
                 self._commitstack()
                 self._movebookmarks(tr)
@@ -1006,6 +1005,11 b' def absorbcmd(ui, repo, *pats, **opts):'
     Returns 0 on success, 1 if all chunks were ignored and nothing amended.
     """
     opts = pycompat.byteskwargs(opts)
+
+    with repo.wlock(), repo.lock():
+        if not opts['dry_run']:
+            cmdutil.checkunfinished(repo)
+
     state = absorb(ui, repo, pats=pats, opts=opts)
     if sum(s[0] for s in state.chunkstats.values()) == 0:
         return 1