bundle: add an experimental knob to include obsmarkers in bundle

The "hg bundle" command is a good place to test if the inclusion of obsmarkers
within a bundle is working well (part exists, content is correct etc). So we
add a way to have them included.

Ideally, this would be controlled by a change around bundlespec (bundlespec
"v3" + arguments). However, my main goal is to have obsmarkers included in
bundle created by the 'hg strip' command, not the 'hg bundle' so for now I'm
avoiding the detour through bundlespec rework territory.

Better debug output for obsmarkers in 'debugbundle' will be added in later
changesets. The 'test-obsolete-bundle-strip.t' test will also get updated in a
later changeset to keep the current changeset smaller.

mercurial/bundle2.py

@@ -1348,7 +1348,10 b' def writenewbundle(ui, repo, source, fil'
     elif not bundletype.startswith('HG20'):
         raise error.ProgrammingError('unknown bundle type: %s' % bundletype)
 
-    bundle = bundle20(ui)
+    caps = {}
+    if 'obsolescence' in opts:
+        caps['obsmarkers'] = ('V1',)
+    bundle = bundle20(ui, caps)
     bundle.setcompression(compression, compopts)
     _addpartsfromopts(ui, repo, bundle, source, outgoing, opts)
     chunkiter = bundle.getchunks()
@@ -1377,6 +1380,10 b' def _addpartsfromopts(ui, repo, bundler,'
 
     addparttagsfnodescache(repo, bundler, outgoing)
 
+    if opts.get('obsolescence', False):
+        obsmarkers = repo.obsstore.relevantmarkers(outgoing.missing)
+        buildobsmarkerspart(bundler, obsmarkers)
+
 def addparttagsfnodescache(repo, bundler, outgoing):
     # we include the tags fnode cache for the bundle changeset
     # (as an optional parts)

mercurial/commands.py

@@ -1326,6 +1326,8 b' def bundle(ui, repo, fname, dest=None, *'
 
 
     contentopts = {'cg.version': cgversion}
+    if repo.ui.configbool('experimental', 'evolution.bundle-obsmarker', False):
+        contentopts['obsolescence'] = True
     bundle2.writenewbundle(ui, repo, 'bundle', fname, bversion, outgoing,
                            contentopts, compression=bcompression,
                            compopts=compopts)

tests/test-obsolete-changeset-exchange.t

@@ -83,6 +83,21 b' check that bundle is not affected'
   adding file changes
   added 1 changesets with 0 changes to 1 files (+1 heads)
   (run 'hg heads' to see heads)
+
+check-that bundle can contain markers:
+
+  $ hg bundle --hidden --rev f89bcc95eba5 --base "f89bcc95eba5^" ../f89bcc95eba5-obs.hg --config experimental.evolution.bundle-obsmarker=1
+  1 changesets found
+  $ hg debugbundle ../f89bcc95eba5.hg
+  Stream params: sortdict([('Compression', 'BZ')])
+  changegroup -- "sortdict([('version', '02'), ('nbchanges', '1')])"
+      f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
+  $ hg debugbundle ../f89bcc95eba5-obs.hg
+  Stream params: sortdict([('Compression', 'BZ')])
+  changegroup -- "sortdict([('version', '02'), ('nbchanges', '1')])"
+      f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
+  obsmarkers -- 'sortdict()'
+
   $ cd ..
 
 pull does not fetch excessive changesets when common node is hidden (issue4982)