Bug 1255588 - Disable selftest.py on 10.7 builders (we now only support running 10.9+). r=jmaher.

testing/xpcshell/moz.build

@@ -6,9 +6,12 @@
 
 TEST_DIRS += ['example']
 
-PYTHON_UNIT_TESTS += [
-    'selftest.py',
-]
+if CONFIG['HOST_OS_ARCH'] != 'Darwin':
+    # Disabled on Mac due to our builders still being on MacOS 10.7,
+    # see bug 1255588
+    PYTHON_UNIT_TESTS += [
+        'selftest.py',
+    ]
 
 TESTING_JS_MODULES += [
     'dbg-actors.js',