hgweb: remove Python 3 conditional

We probably have a better tobytes() implementation somewhere in pycompat.
But I don't want to bloat scope of this commit.

Differential Revision: https://phab.mercurial-scm.org/D12308

mercurial/hgweb/request.py

@@ -160,12 +160,10 b' def parserequestfromenv(env, reponame=No'
     # TODO enable this once we fix internal violations.
     # wsgiref.validate.check_environ(env)
 
-    # PEP-0333 states that environment keys and values are native strings
-    # (bytes on Python 2 and str on Python 3). The code points for the Unicode
-    # strings on Python 3 must be between \00000-\000FF. We deal with bytes
-    # in Mercurial, so mass convert string keys and values to bytes.
-    if pycompat.ispy3:
-
+    # PEP-0333 states that environment keys and values are native strings.
+    # The code points for the Unicode strings on Python 3 must be between
+    # \00000-\000FF. We deal with bytes in Mercurial, so mass convert string
+    # keys and values to bytes.
         def tobytes(s):
             if not isinstance(s, str):
                 return s