This fix ensures that QDomElement::setAttributeNode() correctly replaces
an existing attribute with the same name. Previously, calling
setAttributeNode() with a new attribute of the same name resulted in
both the old and new attributes being present, violating the expected
behavior described in the documentation.
Fixes: QTBUG-15125
Pick-to: 6.9 6.8 6.5
Change-Id: Ibdda37a65f6e754d9f7e68e725d3438bbb2d9e0c
Reviewed-by: Mate Barany <mate.barany@qt.io>
8c99134584