test: Create all intermediary maildirs

Don't fail if root maildir folder does not exist it. Create it recursively.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>

test/OLItest/TestRunner.py

@@ -108,7 +108,7 @@ class OLITestLib():
         maildir = os.path.join(cls.testdir, 'mail', folder)
         for subdir in ('','tmp','cur','new'):
             try:
-                os.mkdir(os.path.join(maildir, subdir))
+                os.makedirs(os.path.join(maildir, subdir))
             except OSError as e:
                 if e.errno != 17: # 'already exists' is ok.
                     raise