transaction: build changes['revs'] as range instead of a set

Revisions are added consecutively, so a range can easily represent them
in the changes list. This saves around 45 Bytes / revision on 64bit
platforms and reduces the memory footprint of issue5691 by 15MB.

Don't copy changes['revs'] in getobsoleted. Ranges have a very efficient
contains implementation already.

Differential Revision: https://phab.mercurial-scm.org/D1615

mercurial/changelog.py

@@ -541,5 +541,10 b' class changelog(revlog.revlog):'
                                                    *args, **kwargs)
         revs = transaction.changes.get('revs')
         if revs is not None:
-            revs.add(rev)
+            if revs:
+                assert revs[-1] + 1 == rev
+                revs = xrange(revs[0], rev + 1)
+            else:
+                revs = xrange(rev, rev + 1)
+            transaction.changes['revs'] = revs
         return node

mercurial/localrepo.py

@@ -1275,7 +1275,7 b' class localrepository(object):'
                                      validator=validate,
                                      releasefn=releasefn,
                                      checkambigfiles=_cachedfiles)
-        tr.changes['revs'] = set()
+        tr.changes['revs'] = xrange(0, 0)
         tr.changes['obsmarkers'] = set()
         tr.changes['phases'] = {}
         tr.changes['bookmarks'] = {}

mercurial/obsutil.py

@@ -441,12 +441,12 b' def getobsoleted(repo, tr):'
     public = phases.public
     addedmarkers = tr.changes.get('obsmarkers')
     addedrevs = tr.changes.get('revs')
-    seenrevs = set(addedrevs)
+    seenrevs = set()
     obsoleted = set()
     for mark in addedmarkers:
         node = mark[0]
         rev = torev(node)
-        if rev is None or rev in seenrevs:
+        if rev is None or rev in seenrevs or rev in addedrevs:
             continue
         seenrevs.add(rev)
         if phase(repo, rev) == public:

mercurial/scmutil.py

@@ -1262,7 +1262,7 b' def registersummarycallback(repo, otr, t'
         @reportsummary
         def reportnewcs(repo, tr):
             """Report the range of new revisions pulled/unbundled."""
-            newrevs = list(tr.changes.get('revs', set()))
+            newrevs = tr.changes.get('revs', xrange(0, 0))
             if not newrevs:
                 return