py3: replace pycompat.getenv with encoding.environ.get

pycompat.getenv returns os.getenvb on py3 which is not available on Windows.
This patch replaces them with encoding.environ.get and checks to ensure no
new instances of os.getenv or os.setenv are introduced.

contrib/check-code.py

@@ -465,9 +465,10 b' py3pats = ['
     (r'os\.sep', "use pycompat.ossep instead (py3)"),
     (r'os\.pathsep', "use pycompat.ospathsep instead (py3)"),
     (r'os\.altsep', "use pycompat.osaltsep instead (py3)"),
-    (r'os\.getenv', "use pycompat.osgetenv instead (py3)"),
     (r'sys\.platform', "use pycompat.sysplatform instead (py3)"),
     (r'getopt\.getopt', "use pycompat.getoptb instead (py3)"),
+    (r'os\.getenv', "use encoding.environ.get instead"),
+    (r'os\.setenv', "modifying the environ dict is not preferred"),
   ],
   # warnings
   [],

hgext/largefiles/lfutil.py

@@ -19,6 +19,7 b' from mercurial.i18n import _'
 
 from mercurial import (
     dirstate,
+    encoding,
     error,
     httpconnection,
     match as matchmod,
@@ -74,19 +75,19 b' def _usercachedir(ui):'
     if path:
         return path
     if pycompat.osname == 'nt':
-        appdata = pycompat.osgetenv('LOCALAPPDATA',\
-                        pycompat.osgetenv('APPDATA'))
+        appdata = encoding.environ.get('LOCALAPPDATA',\
+                        encoding.environ.get('APPDATA'))
         if appdata:
             return os.path.join(appdata, longname)
     elif platform.system() == 'Darwin':
-        home = pycompat.osgetenv('HOME')
+        home = encoding.environ.get('HOME')
         if home:
             return os.path.join(home, 'Library', 'Caches', longname)
     elif pycompat.osname == 'posix':
-        path = pycompat.osgetenv('XDG_CACHE_HOME')
+        path = encoding.environ.get('XDG_CACHE_HOME')
         if path:
             return os.path.join(path, longname)
-        home = pycompat.osgetenv('HOME')
+        home = encoding.environ.get('HOME')
         if home:
             return os.path.join(home, '.cache', longname)
     else:

mercurial/profiling.py

@@ -12,8 +12,8 b' import time'
 
 from .i18n import _
 from . import (
+    encoding,
     error,
-    pycompat,
     util,
 )
 
@@ -120,7 +120,7 b' def profile(ui):'
     Profiling is active when the context manager is active. When the context
     manager exits, profiling results will be written to the configured output.
     """
-    profiler = pycompat.osgetenv('HGPROF')
+    profiler = encoding.environ.get('HGPROF')
     if profiler is None:
         profiler = ui.config('profiling', 'type', default='stat')
     if profiler not in ('ls', 'stat', 'flame'):

mercurial/pycompat.py

@@ -46,7 +46,6 b' if ispy3:'
     ospathsep = os.pathsep.encode('ascii')
     ossep = os.sep.encode('ascii')
     osaltsep = os.altsep
-    osgetenv = os.getenvb
     if osaltsep:
         osaltsep = osaltsep.encode('ascii')
     # os.getcwd() on Python 3 returns string, but it has os.getcwdb() which
@@ -169,7 +168,6 b' else:'
     sysargv = sys.argv
     sysplatform = sys.platform
     getcwd = os.getcwd
-    osgetenv = os.getenv
     sysexecutable = sys.executable
     shlexsplit = shlex.split
 

mercurial/url.py

@@ -15,10 +15,10 b' import socket'
 
 from .i18n import _
 from . import (
+    encoding,
     error,
     httpconnection as httpconnectionmod,
     keepalive,
-    pycompat,
     sslutil,
     util,
 )
@@ -81,7 +81,7 b' class passwordmgr(object):'
 class proxyhandler(urlreq.proxyhandler):
     def __init__(self, ui):
         proxyurl = (ui.config("http_proxy", "host") or
-                        pycompat.osgetenv('http_proxy'))
+                        encoding.environ.get('http_proxy'))
         # XXX proxyauthinfo = None
 
         if proxyurl:
@@ -99,7 +99,7 b' class proxyhandler(urlreq.proxyhandler):'
             no_list.extend([p.lower() for
                             p in ui.configlist("http_proxy", "no")])
             no_list.extend([p.strip().lower() for
-                            p in pycompat.osgetenv("no_proxy", '').split(',')
+                            p in encoding.environ.get("no_proxy", '').split(',')
                             if p.strip()])
             # "http_proxy.always" config is for running tests on localhost
             if ui.configbool("http_proxy", "always"):