Backed out 2 changesets (bug 1396582) for build bustage "ImportError: No module named which". r=backout a=backout on a CLOSED TREE

Backed out changeset a677efcd8768 (bug 1396582)
Backed out changeset 4e81669959ed (bug 1396582)

build/moz.configure/init.configure

@@ -203,6 +203,7 @@ option(env='PYTHON', nargs=1, help='Python interpreter')
 @imports('subprocess')
 @imports(_from='mozbuild.configure.util', _import='LineIO')
 @imports(_from='mozbuild.virtualenv', _import='VirtualenvManager')
+@imports(_from='mozbuild.virtualenv', _import='verify_python_version')
 @imports('distutils.sysconfig')
 def virtualenv_python(env_python, build_env, mozconfig, help):
     if help:
@@ -223,28 +224,8 @@ def virtualenv_python(env_python, build_env, mozconfig, help):
         elif 'PYTHON' in mozconfig['vars']['modified']:
             python = mozconfig['vars']['modified']['PYTHON'][1]
 
-    minimum_version = Version('2.7.3')
+    with LineIO(lambda l: log.error(l)) as out:
-    major, minor, micro = sys.version_info[:3]
+        verify_python_version(out)
-    our_version = Version('%d.%d.%d' % (major, minor, micro))
-
-    if major != 2 or our_version < minimum_version:
-        msg = ('Python %s or greater (but not Python 3) is required to build. '
-              'You are running Python %s. ' % (minimum_version, our_version))
-
-        if os.name == 'nt':
-            msg += ('Please upgrade to the latest MozillaBuild development '
-                   'environment. See https://developer.mozilla.org/en-US/docs/Developer_Guide/Build_Instructions/Windows_Prerequisites')
-        else:
-            msg += ('Run `mach bootstrap` to ensure your system is up to date. '
-                   'If you still receive this error afterwards, your shell '
-                   'environment is likely detecting another Python version. '
-                   'Ensure a modern Python can be found in the paths defined '
-                   'by the $PATH environment variable. Or set the PYTHON '
-                   'environment or mozconfig variable to specify which Python '
-                   'interpreter to use.')
-
-        die(msg)
-
     topsrcdir, topobjdir = build_env.topsrcdir, build_env.topobjdir
     if topobjdir.endswith('/js/src'):
         topobjdir = topobjdir[:-7]

python/mozbuild/mozbuild/virtualenv.py

@@ -20,6 +20,24 @@ IS_NATIVE_WIN = (sys.platform == 'win32' and os.sep == '\\')
 IS_MSYS2 = (sys.platform == 'win32' and os.sep == '/')
 IS_CYGWIN = (sys.platform == 'cygwin')
 
+# Minimum version of Python required to build.
+MINIMUM_PYTHON_VERSION = LooseVersion('2.7.3')
+MINIMUM_PYTHON_MAJOR = 2
+
+
+UPGRADE_WINDOWS = '''
+Please upgrade to the latest MozillaBuild development environment. See
+https://developer.mozilla.org/en-US/docs/Developer_Guide/Build_Instructions/Windows_Prerequisites
+'''.lstrip()
+
+UPGRADE_OTHER = '''
+Run |mach bootstrap| to ensure your system is up to date.
+
+If you still receive this error, your shell environment is likely detecting
+another Python version. Ensure a modern Python can be found in the paths
+defined by the $PATH environment variable and try again.
+'''.lstrip()
+
 
 class VirtualenvManager(object):
     """Contains logic for managing virtualenvs for building the tree."""
@@ -505,3 +523,47 @@ class VirtualenvManager(object):
         # self.python_path. However, this seems more risk than it's worth.
         subprocess.check_call([os.path.join(self.bin_path, 'pip')] + args,
             stderr=subprocess.STDOUT)
+
+
+def verify_python_version(log_handle):
+    """Ensure the current version of Python is sufficient."""
+    major, minor, micro = sys.version_info[:3]
+
+    our = LooseVersion('%d.%d.%d' % (major, minor, micro))
+
+    if major != MINIMUM_PYTHON_MAJOR or our < MINIMUM_PYTHON_VERSION:
+        log_handle.write('Python %s or greater (but not Python 3) is '
+            'required to build. ' % MINIMUM_PYTHON_VERSION)
+        log_handle.write('You are running Python %s.\n' % our)
+
+        if os.name in ('nt', 'ce'):
+            log_handle.write(UPGRADE_WINDOWS)
+        else:
+            log_handle.write(UPGRADE_OTHER)
+
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    if len(sys.argv) < 5:
+        print('Usage: populate_virtualenv.py /path/to/topsrcdir /path/to/topobjdir /path/to/virtualenv /path/to/virtualenv_manifest')
+        sys.exit(1)
+
+    verify_python_version(sys.stdout)
+
+    topsrcdir, topobjdir, virtualenv_path, manifest_path = sys.argv[1:5]
+    populate = False
+
+    # This should only be called internally.
+    if sys.argv[1] == 'populate':
+        populate = True
+        topsrcdir, topobjdir, virtualenv_path, manifest_path = sys.argv[2:]
+
+    manager = VirtualenvManager(topsrcdir, topobjdir, virtualenv_path,
+        sys.stdout, manifest_path)
+
+    if populate:
+        manager.populate()
+    else:
+        manager.ensure()
+