automation: make system3 the default for run-tests-linux
We'll soon drop support for Python 2.7. Let's use Python 3 by
default.
Differential Revision: https://phab.mercurial-scm.org/D12261
--- a/contrib/automation/hgautomation/cli.py Sat Feb 19 18:04:49 2022 -0700
+++ b/contrib/automation/hgautomation/cli.py Sat Feb 19 18:17:14 2022 -0700
@@ -480,7 +480,7 @@
'pypy3.5',
'pypy3.6',
},
- default='system2',
+ default='system3',
)
sp.add_argument(
'test_flags',