py3: replace str with bytes in isinstance()

We were using str because on Python 2, str were bytes but now we have to use
bytes. Otherwise the if conditions fails and we have weird results from commands
on Python 3.

mercurial/hg.py

@@ -477,7 +477,7 b' def clone(ui, peeropts, source, dest=Non'
     remote's path/URL. Defaults to "identity."
     """
 
-    if isinstance(source, str):
+    if isinstance(source, bytes):
         origsource = ui.expandpath(source)
         source, branch = parseurl(origsource, branch)
         srcpeer = peer(ui, peeropts, source)

mercurial/templatekw.py

@@ -126,7 +126,7 b' def _showlist(name, values, mapping, plu'
             yield templ(noname, **mapping)
         return
     if name not in templ:
-        if isinstance(values[0], str):
+        if isinstance(values[0], bytes):
             yield separator.join(values)
         else:
             for v in values:

mercurial/templater.py

@@ -1101,7 +1101,7 b' stringify = templatefilters.stringify'
 def _flatten(thing):
     '''yield a single stream from a possibly nested set of iterators'''
     thing = templatekw.unwraphybrid(thing)
-    if isinstance(thing, str):
+    if isinstance(thing, bytes):
         yield thing
     elif thing is None:
         pass
@@ -1110,7 +1110,7 b' def _flatten(thing):'
     else:
         for i in thing:
             i = templatekw.unwraphybrid(i)
-            if isinstance(i, str):
+            if isinstance(i, bytes):
                 yield i
             elif i is None:
                 pass