merge: mark .hgsubstate as possibly dirty before submerge for consistency Before this patch, failure of updating subrepos may cause inconsistent ".hgsubstate". For example: 1. dirstate entry for ".hgsubstate" of the parent repo is filled with valid size/date (via "hg state" or so) 2. "hg update" is invoked at the parent repo 3. ".hgsubstate" of the parent repo is updated on the filesystem as a part of "g"(et) action in "merge.applyupdates" 4. it is assumed that size/date of ".hgsubstate" on the filesystem aren't changed from ones at (1) this is not so difficult condition, because just changing hash ids (every ids are same in length) in ".hgsubstate" doesn't change the file size of it 5. "subrepo.submerge()" is invoked to update subrepos 6. failure of updating in one of subrepos raises exception (e.g. "untracked file differs") 7. "hg update" is aborted without updating dirstate of the parent repo dirstate entry for ".hgsubstate" still holds size/date at (1) Then, ".hgsubstate" of the parent repo is treated as "CLEAN" unexpectedly, because updating ".hgsubstate" at (3) doesn't change size/date of it on the filesystem: see assumption at (4). This inconsistent ".hgsubstate" status causes unexpected behavior, for example: - "hg revert" forgets to revert ".hgsubstate" - "hg update" misunderstands that (not yet updated) subrepos diverge (then, it shows the prompt to confirm user's decision) To avoid inconsistent ".hgsubstate" status above, this patch marks ".hgsubstate" as possibly dirty before "submerge" invocation. "normallookup"-ed (= dirty) dirstate should be written out, even if processing is aborted by failure. This patch marks ".hgsubstate" as possibly dirty before "submerge", also when it is removed or merged while merging, for safety. This should prevent Mercurial from misunderstanding inconsistent ".hgsubstate" as clean. To satisfy conditions at (1) and (4) above, this patch uses "hg status --config debug.dirstate.delaywrite=2" (to fill valid size/date into dirstate) and "touch" (to fix date of the file).

--- a/mercurial/merge.py	Tue Jan 27 12:33:56 2015 +0000
+++ b/mercurial/merge.py	Fri Jan 30 04:59:05 2015 +0900
@@ -741,7 +741,15 @@
 
     numupdates = sum(len(l) for m, l in actions.items() if m != 'k')
 
+    def dirtysubstate():
+        # mark '.hgsubstate' as possibly dirty forcibly, because
+        # modified '.hgsubstate' is misunderstood as clean,
+        # when both st_size/st_mtime of '.hgsubstate' aren't changed,
+        # even if "submerge" fails and '.hgsubstate' is inconsistent
+        repo.dirstate.normallookup('.hgsubstate')
+
     if [a for a in actions['r'] if a[0] == '.hgsubstate']:
+        dirtysubstate()
         subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
 
     # remove in parallel (must come first)
@@ -760,6 +768,7 @@
     updated = len(actions['g'])
 
     if [a for a in actions['g'] if a[0] == '.hgsubstate']:
+        dirtysubstate()
         subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
 
     # forget (manifest only, just log it) (must come first)
@@ -785,6 +794,7 @@
         z += 1
         progress(_updating, z, item=f, total=numupdates, unit=_files)
         if f == '.hgsubstate': # subrepo states need updating
+            dirtysubstate()
             subrepo.submerge(repo, wctx, mctx, wctx.ancestor(mctx),
                              overwrite)
             continue

--- a/tests/test-subrepo.t	Tue Jan 27 12:33:56 2015 +0000
+++ b/tests/test-subrepo.t	Fri Jan 30 04:59:05 2015 +0900
@@ -758,6 +758,8 @@
 
   $ echo issue3276_ok > repo/s/b
   $ hg -R repo2 push -f -q
+  $ touch -t 200001010000 repo/.hgsubstate
+  $ hg -R repo status --config debug.dirstate.delaywrite=2 repo/.hgsubstate
   $ hg -R repo update
   b: untracked file differs
   abort: untracked files in working directory differ from files in requested revision (in subrepo s)
@@ -766,6 +768,7 @@
   $ cat repo/s/b
   issue3276_ok
   $ rm repo/s/b
+  $ touch -t 200001010000 repo/.hgsubstate
   $ hg -R repo revert --all
   reverting repo/.hgsubstate (glob)
   reverting subrepo s