Do not ignore substitutions with set comment

CHANGELOG.rst

@@ -9,6 +9,12 @@ and this project adheres to `Semantic Versioning`_.
 Unreleased
 ----------
 
+Fixed
+~~~~~
+
+* With ignoring of incomplete subsitutions enabled, 
+  substitutions which consisted just of a comment were skipped.
+
 `2.1.2`_ - 2022-02-06
 ---------------------
 

aleksis/apps/untis/util/mysql/importers/substitutions.py

@@ -147,6 +147,7 @@ def import_substitutions(
                     and not teachers
                     and not cancelled
                     and not cancelled_for_teachers
+                    and not comment
                 ):
                     continue