Bug 1544758 Perma tier 2 [taskcluster:error] exit status 1 r=Bebe,jmaher

Differential Revision: https://phabricator.services.mozilla.com/D28184

--HG--
extra : moz-landing-system : lando

taskcluster/taskgraph/transforms/tests.py

@@ -1011,6 +1011,7 @@ def split_e10s(config, tests):
             if group != '?':
                 group += '-1proc'
             test['treeherder-symbol'] = join_symbol(group, symbol)
+            if get_mobile_project(test) not in ['fennec']:
                 test['mozharness']['extra-options'].append('--disable-e10s')
             yield test