tests: Print remaining jobs in test_runner.py

This helps finding out which tests fail to finish.

test/functional/test_runner.py

@@ -477,6 +477,11 @@ class TestHandler:
                               log_stderr))
         if not self.jobs:
             raise IndexError('pop from empty list')
+
+        # Print remaining running jobs when all jobs have been started.
+        if not self.test_list:
+            print("Remaining jobs: [{}]".format(", ".join(j[0] for j in self.jobs)))
+
         dot_count = 0
         while True:
             # Return first proc that finishes