XML export without specifying 'XML' extension leads to failure

(ale) I did some tests with all versions and I had too the export problem, however I think I found a way and maybe a bug
To make a long story short... the problem is in the name for the exported XML file: if we omit the .xml extension for the name, in the save dialog, the export fails, if we explicitly set the .xml extension in the name the export succeed.