debugdiscovery: small internal refactoring

The part of the code displaying statistic is made independant from the one
running the discovery. In the same do, the declaration of the discovery
function is a bit simplified.

mercurial/debugcommands.py

@@ -785,8 +785,10 b' def debugdiscovery(ui, repo, remoteurl="'
     # make sure tests are repeatable
     random.seed(int(opts['seed']))
 
+
+
+    if opts.get('old'):
     def doit(pushedrevs, remoteheads, remote=remote):
-        if opts.get('old'):
             if not util.safehasattr(remote, 'branches'):
                 # enable in-client legacy support
                 remote = localrepo.locallegacypeer(remote.local())
@@ -800,13 +802,21 b' def debugdiscovery(ui, repo, remoteurl="'
                 clnode = repo.changelog.node
                 common = repo.revs('heads(::%ln)', common)
                 common = {clnode(r) for r in common}
+            return common, hds
         else:
+        def doit(pushedrevs, remoteheads, remote=remote):
             nodes = None
             if pushedrevs:
                 revs = scmutil.revrange(repo, pushedrevs)
                 nodes = [repo[r].node() for r in revs]
             common, any, hds = setdiscovery.findcommonheads(ui, repo, remote,
                                                             ancestorsof=nodes)
+            return common, hds
+
+    remoterevs, _checkout = hg.addbranchrevs(repo, remote, branches, revs=None)
+    localrevs = opts['rev']
+    common, hds = doit(localrevs, remoterevs)
+
         common = set(common)
         rheads = set(hds)
         lheads = set(repo.heads())
@@ -817,10 +827,6 b' def debugdiscovery(ui, repo, remoteurl="'
         elif rheads <= common:
             ui.write(("remote is subset\n"))
 
-    remoterevs, _checkout = hg.addbranchrevs(repo, remote, branches, revs=None)
-    localrevs = opts['rev']
-    doit(localrevs, remoterevs)
-
 _chunksize = 4 << 10
 
 @command('debugdownload',