py3: iterate bytes as a byte string in dagparser.py

mercurial/dagparser.py

@@ -181,7 +181,7 b' def parsedag(desc):'
         else:
             return labels[ref]
 
-    chiter = (c for c in desc)
+    chiter = pycompat.iterbytestr(desc)
 
     def nextch():
         return next(chiter, '\0')

tests/test-doctest.py

@@ -48,8 +48,7 b" testmod('mercurial.changelog')"
 testmod('mercurial.color')
 testmod('mercurial.config')
 testmod('mercurial.context')
-testmod('mercurial.dagparser', optionflags=doctest.NORMALIZE_WHITESPACE,
-        py3=False)  # py3: use of str()
+testmod('mercurial.dagparser', optionflags=doctest.NORMALIZE_WHITESPACE)
 testmod('mercurial.dispatch')
 testmod('mercurial.encoding', py3=False)  # py3: multiple encoding issues
 testmod('mercurial.formatter', py3=False)  # py3: write bytes to stdout