py3: replace os.pathsep with pycompat.ospathsep

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.

--- a/mercurial/posix.py	Sat Dec 17 19:36:40 2016 +0530
+++ b/mercurial/posix.py	Sat Dec 17 19:47:17 2016 +0530
@@ -23,6 +23,7 @@
 from .i18n import _
 from . import (
     encoding,
+    pycompat,
 )
 
 posixfile = open
@@ -461,7 +462,7 @@
     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

--- a/mercurial/scmwindows.py	Sat Dec 17 19:36:40 2016 +0530
+++ b/mercurial/scmwindows.py	Sat Dec 17 19:47:17 2016 +0530
@@ -4,6 +4,7 @@
 
 from . import (
     osutil,
+    pycompat,
     util,
     win32,
 )
@@ -33,7 +34,7 @@
     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):

--- a/mercurial/windows.py	Sat Dec 17 19:36:40 2016 +0530
+++ b/mercurial/windows.py	Sat Dec 17 19:47:17 2016 +0530
@@ -18,6 +18,7 @@
 from . import (
     encoding,
     osutil,
+    pycompat,
     win32,
 )
 
@@ -303,7 +304,7 @@
     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 @@
     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