commit 85fe847fa54659690b8ce173b619b844a8ef58f5
Author: Christian Ehringfeld <c.ehringfeld@mailbox.org>
Date:   Sun Jan 13 10:28:11 2019 +0100

    wrong usage of qmutablehash

diff --git a/src/querybuilder.cpp b/src/querybuilder.cpp
index 34d262e..5ee87d4 100644
--- a/src/querybuilder.cpp
+++ b/src/querybuilder.cpp
@@ -999,7 +999,7 @@ QHash<QString, Relation> QueryBuilder::processRelations(
     while (i.hasNext()) {
         i.next();
         if (usedRelations.contains(i.key())) {
-            relations.remove(i.key());
+            i.remove();
         } else {
             usedRelations.insert(i.key(), i.value());
         }