contrib: simplify the genosxversion.py command to find the hg libraries

I forget what problem I ran into while trying to teach the makefile to use a
non-system python.  (It might have ben missing hg-evolve and/or keyring, but
`check_output()` was raising an error.)  This still isn't great because it will
return non zero for something like the username not being set, even though we
aren't asking for it.  But I suppose it's still useful to simplify.

Differential Revision: https://phab.mercurial-scm.org/D6753

contrib/genosxversion.py

@@ -1,130 +1,129 b''
 #!/usr/bin/env python2
 from __future__ import absolute_import, print_function
 
 import argparse
-import json
 import os
 import subprocess
 import sys
 
 # Always load hg libraries from the hg we can find on $PATH.
-hglib = json.loads(subprocess.check_output(
-    ['hg', 'debuginstall', '-Tjson']))[0]['hgmodules']
+hglib = subprocess.check_output(
+    ['hg', 'debuginstall', '-T', '{hgmodules}'])
 sys.path.insert(0, os.path.dirname(hglib))
 
 from mercurial import util
 
 ap = argparse.ArgumentParser()
 ap.add_argument('--paranoid',
                 action='store_true',
                 help=("Be paranoid about how version numbers compare and "
                       "produce something that's more likely to sort "
                       "reasonably."))
 ap.add_argument('--selftest', action='store_true', help='Run self-tests.')
 ap.add_argument('versionfile', help='Path to a valid mercurial __version__.py')
 
 def paranoidver(ver):
     """Given an hg version produce something that distutils can sort.
 
     Some Mac package management systems use distutils code in order to
     figure out upgrades, which makes life difficult. The test case is
     a reduced version of code in the Munki tool used by some large
     organizations to centrally manage OS X packages, which is what
     inspired this kludge.
 
     >>> paranoidver('3.4')
     '3.4.0'
     >>> paranoidver('3.4.2')
     '3.4.2'
     >>> paranoidver('3.0-rc+10')
     '2.9.9999-rc+10'
     >>> paranoidver('4.2+483-5d44d7d4076e')
     '4.2.0+483-5d44d7d4076e'
     >>> paranoidver('4.2.1+598-48d1e1214d8c')
     '4.2.1+598-48d1e1214d8c'
     >>> paranoidver('4.3-rc')
     '4.2.9999-rc'
     >>> paranoidver('4.3')
     '4.3.0'
     >>> from distutils import version
     >>> class LossyPaddedVersion(version.LooseVersion):
     ...     '''Subclass version.LooseVersion to compare things like
     ...     "10.6" and "10.6.0" as equal'''
     ...     def __init__(self, s):
     ...             self.parse(s)
     ...
     ...     def _pad(self, version_list, max_length):
     ...         'Pad a version list by adding extra 0 components to the end'
     ...         # copy the version_list so we don't modify it
     ...         cmp_list = list(version_list)
     ...         while len(cmp_list) < max_length:
     ...             cmp_list.append(0)
     ...         return cmp_list
     ...
     ...     def __cmp__(self, other):
     ...         if isinstance(other, str):
     ...             other = MunkiLooseVersion(other)
     ...         max_length = max(len(self.version), len(other.version))
     ...         self_cmp_version = self._pad(self.version, max_length)
     ...         other_cmp_version = self._pad(other.version, max_length)
     ...         return cmp(self_cmp_version, other_cmp_version)
     >>> def testver(older, newer):
     ...   o = LossyPaddedVersion(paranoidver(older))
     ...   n = LossyPaddedVersion(paranoidver(newer))
     ...   return o < n
     >>> testver('3.4', '3.5')
     True
     >>> testver('3.4.0', '3.5-rc')
     True
     >>> testver('3.4-rc', '3.5')
     True
     >>> testver('3.4-rc+10-deadbeef', '3.5')
     True
     >>> testver('3.4.2', '3.5-rc')
     True
     >>> testver('3.4.2', '3.5-rc+10-deadbeef')
     True
     >>> testver('4.2+483-5d44d7d4076e', '4.2.1+598-48d1e1214d8c')
     True
     >>> testver('4.3-rc', '4.3')
     True
     >>> testver('4.3', '4.3-rc')
     False
     """
     major, minor, micro, extra = util.versiontuple(ver, n=4)
     if micro is None:
         micro = 0
     if extra:
         if extra.startswith('rc'):
             if minor == 0:
                 major -= 1
                 minor = 9
             else:
                 minor -= 1
             micro = 9999
             extra = '-' + extra
         else:
             extra = '+' + extra
     else:
         extra = ''
     return '%d.%d.%d%s' % (major, minor, micro, extra)
 
 def main(argv):
     opts = ap.parse_args(argv[1:])
     if opts.selftest:
         import doctest
         doctest.testmod()
         return
     with open(opts.versionfile) as f:
         for l in f:
             if l.startswith('version = b'):
                 # version number is entire line minus the quotes
                 ver = l[len('version = b') + 1:-2]
                 break
     if opts.paranoid:
         print(paranoidver(ver))
     else:
         print(ver)
 
 if __name__ == '__main__':
     main(sys.argv)