This is a follow up of bug report 3159 (I erroneously commited as a bug report
to the SpecialImport functionnality).
Indeed the solution is in 'SpecialExport' and the problem is not in 'SpecialImport'.
In order to facilitate the saving ox XML files, exported from mw, in an
(which is not an immediate operation even on good browsers like firefox,
and even for not-too-stupid users...), we should rely on the Content-Disposition
header (at least, optionaly).
Everything, including the comments, are provided in my new version of file
(Just watch all lines around those including the pattern "// !" in this file)
Or, of course, in the SpecialExport.diff file.
I'll immediately upload these 2 files.