Bug 1233534 - [mozprofile] unable to use a profile generated with recent firefox. r=ahal

--HG--
extra : rebase_source : b9cad07a8d5e5e056704b5a8a6c31b02f66c42e6

testing/mozbase/mozprofile/mozprofile/prefs.py

@@ -165,10 +165,10 @@ class Preferences(object):
         """
 
         marker = '##//' # magical marker
-        lines = [i.strip() for i in mozfile.load(path).readlines() if i.strip()]
+        lines = [i.strip() for i in mozfile.load(path).readlines()]
         _lines = []
         for line in lines:
-            if line.startswith(('#', '//')):
+            if not line.startswith(pref_setter):
                 continue
             if '//' in line:
                 line = line.replace('//', marker)

testing/mozbase/mozprofile/tests/test_preferences.py

@@ -259,6 +259,34 @@ user_pref("webgl.force-enabled", true);
         finally:
             shutil.rmtree(tempdir)
 
+    def test_can_read_prefs_with_multiline_comments(self):
+        """
+        Ensure that multiple comments in the file header do not break reading
+        the prefs (https://bugzilla.mozilla.org/show_bug.cgi?id=1233534).
+        """
+        user_js = tempfile.NamedTemporaryFile(suffix='.js', delete=False)
+        self.addCleanup(mozfile.remove, user_js.name)
+        with user_js:
+            user_js.write("""
+# Mozilla User Preferences
+
+/* Do not edit this file.
+ *
+ * If you make changes to this file while the application is running,
+ * the changes will be overwritten when the application exits.
+ *
+ * To make a manual change to preferences, you can visit the URL about:config
+ */
+
+user_pref("webgl.enabled_for_all_sites", true);
+user_pref("webgl.force-enabled", true);
+""")
+        self.assertEqual(
+            Preferences.read_prefs(user_js.name),
+            [('webgl.enabled_for_all_sites', True),
+             ('webgl.force-enabled', True)]
+        )
+
     def test_json(self):
         _prefs = {"browser.startup.homepage": "http://planet.mozilla.org/"}
         json = '{"browser.startup.homepage": "http://planet.mozilla.org/"}'