Delete broken references to in commandFits (#844)

eos/db/migrations/upgrade19.py

@@ -0,0 +1,20 @@
+"""
+Migration 19
+
+- Deletes broken references to fits from the commandFits table (see GH issue #844)
+"""
+
+import sqlalchemy
+
+
+def upgrade(saveddata_engine):
+    from eos.db import saveddata_session
+
+    sql = """
+          DELETE FROM commandFits
+          WHERE boosterID NOT IN (select ID from fits)
+	      OR boostedID NOT IN (select ID from fits)
+          """
+
+    saveddata_session.execute(sql)
+    saveddata_session.commit()