[PATCH 2 of 2 STABLE V3 STABLE] rewriting: add an option for rewrite commands to use the archived phase

[Boris Feld]

# HG changeset patch
# User Boris Feld <boris.feld at octobus.net>
# Date 1546394872 -3600
#      Wed Jan 02 03:07:52 2019 +0100
# Branch stable
# Node ID c7de05822f70b02d95b7171c81c9360f1986671b
# Parent  4e7166569731150da6c5aca19f4b6c64a3d259a9
# EXP-Topic archived-phase-UX
# Available At https://bitbucket.org/octobus/mercurial-devel/
#              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r c7de05822f70
rewriting: add an option for rewrite commands to use the archived phase

Using the archived phase for cleanup provide the same effect than stripping,
but in a faster, append-only way.

We keep the feature experimental for now until it gets a bit more testing.

diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -497,6 +497,9 @@ coreconfigitem('experimental', 'bundleco
 coreconfigitem('experimental', 'changegroup3',
     default=False,
 )
+coreconfigitem('experimental', 'cleanup-as-archived',
+    default=False,
+)
 coreconfigitem('experimental', 'clientcompressionengines',
     default=list,
 )
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -984,6 +984,7 @@ def cleanupnodes(repo, replacements, ope
         for phase, nodes in toadvance.items():
             phases.advanceboundary(repo, tr, phase, nodes)
 
+        mayusearchived = repo.ui.config('experimental', 'cleanup-as-archived')
         # Obsolete or strip nodes
         if obsolete.isenabled(repo, obsolete.createmarkersopt):
             # If a node is already obsoleted, and we want to obsolete it
@@ -1001,6 +1002,17 @@ def cleanupnodes(repo, replacements, ope
             if rels:
                 obsolete.createmarkers(repo, rels, operation=operation,
                                        metadata=metadata)
+        elif phases.supportinternal(repo) and mayusearchived:
+            # this assume we do not have "unstable" nodes above the cleaned ones
+            allreplaced = set()
+            for ns in replacements.keys():
+                allreplaced.update(ns)
+            if backup:
+                from . import repair # avoid import cycle
+                node = min(allreplaced, key=repo.changelog.rev)
+                repair.backupbundle(repo, allreplaced, allreplaced, node,
+                                    operation)
+            phases.retractboundary(repo, tr, phases.archived, allreplaced)
         else:
             from . import repair # avoid import cycle
             tostrip = list(n for ns in replacements for n in ns)
diff --git a/tests/test-phase-archived.t b/tests/test-phase-archived.t
--- a/tests/test-phase-archived.t
+++ b/tests/test-phase-archived.t
@@ -75,3 +75,69 @@ Test that bundle can unarchive a changes
      date:        Thu Jan 01 00:00:00 1970 +0000
      summary:     root
   
+
+Test that history rewriting command can use the archived phase when allowed to
+------------------------------------------------------------------------------
+
+  $ hg up 'desc(unbundletesting)'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ echo bar >> a
+  $ hg commit --amend --config experimental.cleanup-as-archived=yes
+  $ hg log -G
+  @  changeset:   2:d1e73e428f29
+  |  tag:         tip
+  |  parent:      0:c1863a3840c6
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     unbundletesting
+  |
+  o  changeset:   0:c1863a3840c6
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     root
+  
+  $ hg log -G --hidden
+  @  changeset:   2:d1e73e428f29
+  |  tag:         tip
+  |  parent:      0:c1863a3840c6
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     unbundletesting
+  |
+  | o  changeset:   1:883aadbbf309
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     unbundletesting
+  |
+  o  changeset:   0:c1863a3840c6
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     root
+  
+  $ ls -1 .hg/strip-backup/
+  883aadbbf309-efc55adc-amend.hg
+  883aadbbf309-efc55adc-backup.hg
+  $ hg unbundle .hg/strip-backup/883aadbbf309*amend.hg
+  adding changesets
+  adding manifests
+  adding file changes
+  added 0 changesets with 0 changes to 1 files
+  (run 'hg update' to get a working copy)
+  $ hg log -G
+  @  changeset:   2:d1e73e428f29
+  |  tag:         tip
+  |  parent:      0:c1863a3840c6
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     unbundletesting
+  |
+  | o  changeset:   1:883aadbbf309
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     unbundletesting
+  |
+  o  changeset:   0:c1863a3840c6
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     root
+