# HG changeset patch
# User timeless <timeless@mozdev.org>
# Date 2016-03-09 19:55:45
# Node ID b3a677c82a35e499e84f69245f65e682c4be698f
# Parent  3f9e68864ccc1575ae3f2df14b78df6779daa1f7

debuginstall: expose modulepolicy

With this, you can check for pure easily:
$ HGMODULEPOLICY=py ./hg debuginstall -T "{hgmodulepolicy}"
py

diff --git a/mercurial/__init__.py b/mercurial/__init__.py
--- a/mercurial/__init__.py
+++ b/mercurial/__init__.py
@@ -12,36 +12,13 @@ import os
 import sys
 import zipimport
 
+from . import (
+    policy
+)
+
 __all__ = []
 
-# Rules for how modules can be loaded. Values are:
-#
-#    c - require C extensions
-#    allow - allow pure Python implementation when C loading fails
-#    py - only load pure Python modules
-#
-# By default, require the C extensions for performance reasons.
-modulepolicy = 'c'
-try:
-    from . import __modulepolicy__
-    modulepolicy = __modulepolicy__.modulepolicy
-except ImportError:
-    pass
-
-# PyPy doesn't load C extensions.
-#
-# The canonical way to do this is to test platform.python_implementation().
-# But we don't import platform and don't bloat for it here.
-if '__pypy__' in sys.builtin_module_names:
-    modulepolicy = 'py'
-
-# Our C extensions aren't yet compatible with Python 3. So use pure Python
-# on Python 3 for now.
-if sys.version_info[0] >= 3:
-    modulepolicy = 'py'
-
-# Environment variable can always force settings.
-modulepolicy = os.environ.get('HGMODULEPOLICY', modulepolicy)
+modulepolicy = policy.policy
 
 # Modules that have both Python and C implementations. See also the
 # set of .py files under mercurial/pure/.
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -59,6 +59,7 @@ from . import (
     obsolete,
     patch,
     phases,
+    policy,
     pvec,
     repair,
     revlog,
@@ -2749,6 +2750,8 @@ def debuginstall(ui, **opts):
              '+'.join(hgver.split('+')[1:]))
 
     # compiled modules
+    fm.write('hgmodulepolicy', _("checking module policy (%s)\n"),
+             policy.policy)
     fm.write('hgmodules', _("checking installed modules (%s)...\n"),
              os.path.dirname(__file__))
 
diff --git a/mercurial/policy.py b/mercurial/policy.py
new file mode 100644
--- /dev/null
+++ b/mercurial/policy.py
@@ -0,0 +1,40 @@
+# policy.py - module policy logic for Mercurial.
+#
+# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from __future__ import absolute_import
+
+import os
+import sys
+
+# Rules for how modules can be loaded. Values are:
+#
+#    c - require C extensions
+#    allow - allow pure Python implementation when C loading fails
+#    py - only load pure Python modules
+#
+# By default, require the C extensions for performance reasons.
+policy = 'c'
+try:
+    from . import __modulepolicy__
+    policy = __modulepolicy__.modulepolicy
+except ImportError:
+    pass
+
+# PyPy doesn't load C extensions.
+#
+# The canonical way to do this is to test platform.python_implementation().
+# But we don't import platform and don't bloat for it here.
+if '__pypy__' in sys.builtin_module_names:
+    policy = 'py'
+
+# Our C extensions aren't yet compatible with Python 3. So use pure Python
+# on Python 3 for now.
+if sys.version_info[0] >= 3:
+    policy = 'py'
+
+# Environment variable can always force settings.
+policy = os.environ.get('HGMODULEPOLICY', policy)
diff --git a/tests/test-install.t b/tests/test-install.t
--- a/tests/test-install.t
+++ b/tests/test-install.t
@@ -6,6 +6,7 @@ hg debuginstall
   checking Python lib (*lib*)... (glob)
   checking Mercurial version (*) (glob)
   checking Mercurial custom build (*) (glob)
+  checking module policy (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)
@@ -25,6 +26,7 @@ hg debuginstall JSON
     "encoding": "ascii",
     "encodingerror": null,
     "extensionserror": null,
+    "hgmodulepolicy": "*", (glob)
     "hgmodules": "*mercurial", (glob)
     "hgver": "*", (glob)
     "hgverextra": "*", (glob)
@@ -47,6 +49,7 @@ hg debuginstall with no username
   checking Python lib (*lib*)... (glob)
   checking Mercurial version (*) (glob)
   checking Mercurial custom build (*) (glob)
+  checking module policy (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)
@@ -70,6 +73,7 @@ path variables are expanded (~ is the sa
   checking Python lib (*lib*)... (glob)
   checking Mercurial version (*) (glob)
   checking Mercurial custom build (*) (glob)
+  checking module policy (*) (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking default template (*mercurial?templates?map-cmdline.default) (glob)