pycompat: provide 'ispy3' constant

We compare version_info at several places, which seems enough to define
a constant.

mercurial/bundle2.py

@@ -159,6 +159,7 b' from . import ('
     error,
     obsolete,
     pushkey,
+    pycompat,
     tags,
     url,
     util,
@@ -996,7 +997,7 b' class bundlepart(object):'
             outdebug(ui, 'closing payload chunk')
             # abort current part payload
             yield _pack(_fpayloadsize, 0)
-            if sys.version_info[0] >= 3:
+            if pycompat.ispy3:
                 raise exc_info[0](exc_info[1]).with_traceback(exc_info[2])
             else:
                 exec("""raise exc_info[0], exc_info[1], exc_info[2]""")

mercurial/encoding.py

@@ -10,14 +10,14 b' from __future__ import absolute_import'
 import array
 import locale
 import os
-import sys
 import unicodedata
 
 from . import (
     error,
+    pycompat,
 )
 
-if sys.version_info[0] >= 3:
+if pycompat.ispy3:
     unichr = chr
 
 # These unicode characters are ignored by HFS+ (Apple Technote 1150,
@@ -27,7 +27,7 b' if sys.version_info[0] >= 3:'
            "200c 200d 200e 200f 202a 202b 202c 202d 202e "
            "206a 206b 206c 206d 206e 206f feff".split()]
 # verify the next function will work
-if sys.version_info[0] >= 3:
+if pycompat.ispy3:
     assert set(i[0] for i in _ignore) == set([ord(b'\xe2'), ord(b'\xef')])
 else:
     assert set(i[0] for i in _ignore) == set(["\xe2", "\xef"])

mercurial/pycompat.py

@@ -12,7 +12,9 b' from __future__ import absolute_import'
 
 import sys
 
-if sys.version_info[0] < 3:
+ispy3 = (sys.version_info[0] >= 3)
+
+if not ispy3:
     import cPickle as pickle
     import cStringIO as io
     import httplib
@@ -29,7 +31,7 b' else:'
     import urllib.parse as urlparse
     import xmlrpc.client as xmlrpclib
 
-if sys.version_info[0] >= 3:
+if ispy3:
     import builtins
     import functools
 
@@ -72,7 +74,7 b' class _pycompatstub(object):'
 httpserver = _pycompatstub()
 urlreq = _pycompatstub()
 urlerr = _pycompatstub()
-if sys.version_info[0] < 3:
+if not ispy3:
     import BaseHTTPServer
     import CGIHTTPServer
     import SimpleHTTPServer

mercurial/util.py

@@ -232,7 +232,7 b' class digestchecker(object):'
 try:
     buffer = buffer
 except NameError:
-    if sys.version_info[0] < 3:
+    if not pycompat.ispy3:
         def buffer(sliceable, offset=0):
             return sliceable[offset:]
     else: