Some operating systems don't have the `C.UTF-8` locale installed yet
(for instance, CentOS 7). In such a case, fallback to `en_US.UTF-8` so
that tests can be run.
This follows commit 92ff315.
Some operating systems don't have the `C.UTF-8` locale installed yet
(for instance, CentOS 7). In such a case, fallback to `en_US.UTF-8` so
that tests can be run.
This follows commit 92ff315.