--- a/mercurial/treediscovery.py	Sun Oct 06 09:45:02 2019 -0400
+++ b/mercurial/treediscovery.py	Sun Oct 06 09:48:39 2019 -0400
@@ -39,7 +39,7 @@
 
     if not heads:
         with remote.commandexecutor() as e:
-            heads = e.callcommand('heads', {}).result()
+            heads = e.callcommand(b'heads', {}).result()
 
     if repo.changelog.tip() == nullid:
         base.add(nullid)
@@ -49,7 +49,7 @@
 
     # assume we're closer to the tip than the root
     # and start by examining the heads
-    repo.ui.status(_("searching for changes\n"))
+    repo.ui.status(_(b"searching for changes\n"))
 
     unknown = []
     for h in heads:
@@ -63,14 +63,14 @@
 
     req = set(unknown)
     reqcnt = 0
-    progress = repo.ui.makeprogress(_('searching'), unit=_('queries'))
+    progress = repo.ui.makeprogress(_(b'searching'), unit=_(b'queries'))
 
     # search through remote branches
     # a 'branch' here is a linear segment of history, with four parts:
     # head, root, first parent, second parent
     # (a branch always has two parents (or none) by definition)
     with remote.commandexecutor() as e:
-        branches = e.callcommand('branches', {'nodes': unknown}).result()
+        branches = e.callcommand(b'branches', {b'nodes': unknown}).result()
 
     unknown = collections.deque(branches)
     while unknown:
@@ -80,15 +80,15 @@
             if n[0] in seen:
                 continue
 
-            repo.ui.debug("examining %s:%s\n" % (short(n[0]), short(n[1])))
+            repo.ui.debug(b"examining %s:%s\n" % (short(n[0]), short(n[1])))
             if n[0] == nullid:  # found the end of the branch
                 pass
             elif n in seenbranch:
-                repo.ui.debug("branch already found\n")
+                repo.ui.debug(b"branch already found\n")
                 continue
             elif n[1] and knownnode(n[1]):  # do we know the base?
                 repo.ui.debug(
-                    "found incomplete branch %s:%s\n"
+                    b"found incomplete branch %s:%s\n"
                     % (short(n[0]), short(n[1]))
                 )
                 search.append(n[0:2])  # schedule branch range for scanning
@@ -96,7 +96,7 @@
             else:
                 if n[1] not in seen and n[1] not in fetch:
                     if knownnode(n[2]) and knownnode(n[3]):
-                        repo.ui.debug("found new changeset %s\n" % short(n[1]))
+                        repo.ui.debug(b"found new changeset %s\n" % short(n[1]))
                         fetch.add(n[1])  # earliest unknown
                     for p in n[2:4]:
                         if knownnode(p):
@@ -112,17 +112,17 @@
             reqcnt += 1
             progress.increment()
             repo.ui.debug(
-                "request %d: %s\n" % (reqcnt, " ".join(map(short, r)))
+                b"request %d: %s\n" % (reqcnt, b" ".join(map(short, r)))
             )
             for p in pycompat.xrange(0, len(r), 10):
                 with remote.commandexecutor() as e:
                     branches = e.callcommand(
-                        'branches', {'nodes': r[p : p + 10],}
+                        b'branches', {b'nodes': r[p : p + 10],}
                     ).result()
 
                 for b in branches:
                     repo.ui.debug(
-                        "received %s:%s\n" % (short(b[0]), short(b[1]))
+                        b"received %s:%s\n" % (short(b[0]), short(b[1]))
                     )
                     unknown.append(b)
 
@@ -133,24 +133,24 @@
         progress.increment()
 
         with remote.commandexecutor() as e:
-            between = e.callcommand('between', {'pairs': search}).result()
+            between = e.callcommand(b'between', {b'pairs': search}).result()
 
         for n, l in zip(search, between):
             l.append(n[1])
             p = n[0]
             f = 1
             for i in l:
-                repo.ui.debug("narrowing %d:%d %s\n" % (f, len(l), short(i)))
+                repo.ui.debug(b"narrowing %d:%d %s\n" % (f, len(l), short(i)))
                 if knownnode(i):
                     if f <= 2:
                         repo.ui.debug(
-                            "found new branch changeset %s\n" % short(p)
+                            b"found new branch changeset %s\n" % short(p)
                         )
                         fetch.add(p)
                         base.add(i)
                     else:
                         repo.ui.debug(
-                            "narrowed branch search to %s:%s\n"
+                            b"narrowed branch search to %s:%s\n"
                             % (short(p), short(i))
                         )
                         newsearch.append((p, i))
@@ -161,22 +161,22 @@
     # sanity check our fetch list
     for f in fetch:
         if knownnode(f):
-            raise error.RepoError(_("already have changeset ") + short(f[:4]))
+            raise error.RepoError(_(b"already have changeset ") + short(f[:4]))
 
     base = list(base)
     if base == [nullid]:
         if force:
-            repo.ui.warn(_("warning: repository is unrelated\n"))
+            repo.ui.warn(_(b"warning: repository is unrelated\n"))
         else:
-            raise error.Abort(_("repository is unrelated"))
+            raise error.Abort(_(b"repository is unrelated"))
 
     repo.ui.debug(
-        "found new changesets starting at "
-        + " ".join([short(f) for f in fetch])
-        + "\n"
+        b"found new changesets starting at "
+        + b" ".join([short(f) for f in fetch])
+        + b"\n"
     )
 
     progress.complete()
-    repo.ui.debug("%d total queries\n" % reqcnt)
+    repo.ui.debug(b"%d total queries\n" % reqcnt)
 
     return base, list(fetch), heads