amend: add obsolete support

If the obsolete feature is enabled, `hg commit --amend` marks a
changeset as obsolete instead of stripping it.

mercurial/cmdutil.py

@@ -10,7 +10,7 b' from i18n import _'
 import os, sys, errno, re, tempfile
 import util, scmutil, templater, patch, error, templatekw, revlog, copies
 import match as matchmod
-import subrepo, context, repair, bookmarks, graphmod, revset, phases
+import subrepo, context, repair, bookmarks, graphmod, revset, phases, obsolete
 import lock as lockmod
 
 def parsealiases(cmd):
@@ -1697,12 +1697,20 b' def amend(ui, repo, commitfunc, old, ext'
                         repo._bookmarks[bm] = newid
                     bookmarks.write(repo)
             #commit the whole amend process
+            if obsolete._enabled and newid != old.node():
+                # mark the new changeset as successor of the rewritten one
+                new = repo[newid]
+                obs = [(old, (new,))]
+                if node:
+                    obs.append((ctx, (new,)))
+
+                obsolete.createmarkers(repo, obs)
             tr.close()
         finally:
             tr.release()
-        # Strip the intermediate commit (if there was one) and the amended
-        # commit
-        if newid != old.node():
+        if (not obsolete._enabled) and newid != old.node():
+            # Strip the intermediate commit (if there was one) and the amended
+            # commit
             if node:
                 ui.note(_('stripping intermediate changeset %s\n') % ctx)
             ui.note(_('stripping amended changeset %s\n') % old)

tests/test-commit-amend.t

@@ -370,3 +370,75 b' Preserve phase'
   11: draft
   13: secret
 
+Test amend with obsolete
+---------------------------
+
+Enable obsolete
+
+  $ cat > ${TESTTMP}/obs.py << EOF
+  > import mercurial.obsolete
+  > mercurial.obsolete._enabled = True
+  > EOF
+  $ echo '[extensions]' >> $HGRCPATH
+  $ echo "obs=${TESTTMP}/obs.py" >> $HGRCPATH
+
+
+Amend with no files changes
+
+  $ hg id -n
+  13
+  $ hg ci --amend -m 'babar'
+  $ hg id -n
+  14
+  $ hg log -Gl 3 --style=compact
+  @  14[tip]:11   43df5a5434ad   1970-01-01 00:00 +0000   test
+  |    babar
+  |
+  | o  12:0   2647734878ef   1970-01-01 00:00 +0000   test
+  | |    fork
+  | |
+  o |  11   7e09f708a0e9   1970-01-01 00:00 +0000   test
+  | |    a''
+  | |
+  $ hg log -Gl 4 --hidden --style=compact
+  @  14[tip]:11   43df5a5434ad   1970-01-01 00:00 +0000   test
+  |    babar
+  |
+  | x  13:11   175fafee6f44   1970-01-01 00:00 +0000   test
+  |/     amend for phase
+  |
+  | o  12:0   2647734878ef   1970-01-01 00:00 +0000   test
+  | |    fork
+  | |
+  o |  11   7e09f708a0e9   1970-01-01 00:00 +0000   test
+  | |    a''
+  | |
+
+Amend with files changes
+
+(note: the extra commit over 15 is a temporary junk I would be happy to get
+ride of)
+
+  $ echo 'babar' >> a
+  $ hg commit --amend
+  $ hg log -Gl 6 --hidden --style=compact
+  @  16[tip]:11   31e0a4a1b04a   1970-01-01 00:00 +0000   test
+  |    babar
+  |
+  | x  15   053c696ada75   1970-01-01 00:00 +0000   test
+  | |    temporary amend commit for 43df5a5434ad
+  | |
+  | x  14:11   43df5a5434ad   1970-01-01 00:00 +0000   test
+  |/     babar
+  |
+  | x  13:11   175fafee6f44   1970-01-01 00:00 +0000   test
+  |/     amend for phase
+  |
+  | o  12:0   2647734878ef   1970-01-01 00:00 +0000   test
+  | |    fork
+  | |
+  o |  11   7e09f708a0e9   1970-01-01 00:00 +0000   test
+  | |    a''
+  | |
+
+