.bak file present in sources (5.12 LTS)

In the qt everywhere source tarball (5.12.11) , as well as on git, there is this file with .bak extension

Path: qtbase/tests/auto/xml/sax/qxmlsimplereader/xmldocs/valid/sa/089.xml.bak

This may be a temporary file.

If it is not necessary, may it be removed ? For example with the next release of 5.12 LTS ?

It is also in git

https://github.com/qt/qtbase/blob/5.12.11/tests/auto/xml/sax/qxmlsimplereader/xmldocs/valid/sa/089.xml.bak

It seems it was removed from 5.14