Bug 1195748 - Fix mach auto-logging on Windows. r=gps

We were relying on the log manager's terminal to know whether we're
running on a terminal to turn on auto-logging, but the log manager's
terminal is always None on Windows because blessings imports curses,
which doesn't work on Windows.

So instead, just use a plain os.isatty() call.

The same problem also applies to the show-log command to trigger the
pager (less). At the same time, fix the environment setting for LESS,
as on Windows, unicode literals are not allowed in the environment.

--HG--
extra : rebase_source : 1462849608c8cb86afcb080184efb50caf6d2f9e

python/mozbuild/mozbuild/base.py

@@ -755,7 +755,7 @@ class MachCommandBase(MozbuildObject):
         # Always keep a log of the last command, but don't do that for mach
         # invokations from scripts (especially not the ones done by the build
         # system itself).
-        if (self.log_manager and self.log_manager.terminal and
+        if (os.isatty(sys.stdout.fileno()) and
                 not getattr(self, 'NO_AUTO_LOG', False)):
             self._ensure_state_subdir_exists('.')
             logfile = self._get_state_filename('last_log.json')

python/mozbuild/mozbuild/mach_commands.py

@@ -672,12 +672,12 @@ class Logs(MachCommandBase):
             path = self._get_state_filename('last_log.json')
             log_file = open(path, 'rb')
 
-        if self.log_manager.terminal:
+        if os.isatty(sys.stdout.fileno()):
             env = dict(os.environ)
             if 'LESS' not in env:
                 # Sensible default flags if none have been set in the user
                 # environment.
-                env['LESS'] = 'FRX'
+                env[b'LESS'] = b'FRX'
             less = subprocess.Popen(['less'], stdin=subprocess.PIPE, env=env)
             # Various objects already have a reference to sys.stdout, so we
             # can't just change it, we need to change the file descriptor under