/test_ctests / test_notify1: Print cmdline on failure

Tests sometimes fail with

pytest.fail('file system process terminated prematurely')

And it is not clear what actually happens.

test/test_ctests.py

@@ -75,6 +75,7 @@ def test_notify1(tmpdir, name, notify, output_checker):
         else:
             assert read1 == read2
     except:
+        print("Failure in notify test: '" + str(cmdline) + "'")
         cleanup(mount_process, mnt_dir)
         raise
     else: