py3: replace os.pathsep with pycompat.ospathsep

os.pathsep returns unicode on Python 3. We already have pycompat.ospathsep
which return bytes on Python 3. This patch replaces all the occurrences of
os.pathsep in the codebase (excluding tests) to pycompat.ospathsep.

mercurial/posix.py

@@ -23,6 +23,7 b' import unicodedata'
 from .i18n import _
 from . import (
     encoding,
+    pycompat,
 )
 
 posixfile = open
@@ -461,7 +462,7 b' def findexe(command):'
     if sys.platform == 'plan9':
         return findexisting(os.path.join('/bin', command))
 
-    for path in os.environ.get('PATH', '').split(os.pathsep):
+    for path in os.environ.get('PATH', '').split(pycompat.ospathsep):
         executable = findexisting(os.path.join(path, command))
         if executable is not None:
             return executable

mercurial/scmwindows.py

@@ -4,6 +4,7 b' import os'
 
 from . import (
     osutil,
+    pycompat,
     util,
     win32,
 )
@@ -33,7 +34,7 b' def systemrcpath():'
     if not isinstance(value, str) or not value:
         return rcpath
     value = util.localpath(value)
-    for p in value.split(os.pathsep):
+    for p in value.split(pycompat.ospathsep):
         if p.lower().endswith('mercurial.ini'):
             rcpath.append(p)
         elif os.path.isdir(p):

mercurial/windows.py

@@ -18,6 +18,7 b' from .i18n import _'
 from . import (
     encoding,
     osutil,
+    pycompat,
     win32,
 )
 
@@ -303,7 +304,7 b' def findexe(command):'
     An extension from PATHEXT is found and added if not present.
     If command isn't found None is returned.'''
     pathext = os.environ.get('PATHEXT', '.COM;.EXE;.BAT;.CMD')
-    pathexts = [ext for ext in pathext.lower().split(os.pathsep)]
+    pathexts = [ext for ext in pathext.lower().split(pycompat.ospathsep)]
     if os.path.splitext(command)[1].lower() in pathexts:
         pathexts = ['']
 
@@ -318,7 +319,7 b' def findexe(command):'
     if os.sep in command:
         return findexisting(command)
 
-    for path in os.environ.get('PATH', '').split(os.pathsep):
+    for path in os.environ.get('PATH', '').split(pycompat.ospathsep):
         executable = findexisting(os.path.join(path, command))
         if executable is not None:
             return executable