py3: fix doctests in patch.py to be compatible with Python 3

We were lucky that parsepatch() could concatenate a character slice as if
it were a list of chunks.

mercurial/patch.py

@@ -1490,7 +1490,7 b' def reversehunks(hunks):'
     ...  5
     ...  d
     ... +lastline"""
-    >>> hunks = parsepatch(rawpatch)
+    >>> hunks = parsepatch([rawpatch])
     >>> hunkscomingfromfilterpatch = []
     >>> for h in hunks:
     ...     hunkscomingfromfilterpatch.append(h)
@@ -1501,7 +1501,7 b' def reversehunks(hunks):'
     >>> fp = util.stringio()
     >>> for c in reversedhunks:
     ...      c.write(fp)
-    >>> fp.seek(0)
+    >>> fp.seek(0) or None
     >>> reversedpatch = fp.read()
     >>> print(pycompat.sysstr(reversedpatch))
     diff --git a/folder1/g b/folder1/g

tests/test-doctest.py

@@ -57,7 +57,7 b" testmod('mercurial.hgweb.hgwebdir_mod', "
 testmod('mercurial.match')
 testmod('mercurial.mdiff')
 testmod('mercurial.minirst')
-testmod('mercurial.patch', py3=False)  # py3: bytes[n], etc. ?
+testmod('mercurial.patch')
 testmod('mercurial.pathutil', py3=False)  # py3: os.sep
 testmod('mercurial.parser')
 testmod('mercurial.pycompat')