tests: re-harden test_remote_usage_prog

The meaning of the test is to check that "prog" is not "-c", which was
weakened in 93780dc.

Author: blueyed

testing/test_remote.py

@@ -286,4 +286,8 @@ def test(get_config_parser, request):
 
     result = testdir.runpytest_subprocess("-n1")
     assert result.ret == 1
-    result.stdout.fnmatch_lines(["*usage: *", "*error: my_usage_error"])
+    result.stdout.re_match_lines([
+        "^>       raise UsageError",
+        "^E       .*UsageError: usage: (pytest.py|__main__.py)",
+        "^E       (pytest.py|__main__.py): error: my_usage_error",
+    ])