Support of csv files with .xls extension

Hi All,
Starting with 4.1 csv files with xls extension & also tsv files are opened using 
writer instead of calc, when opening from the start center or from cli without 
'--calc'. While it's clear that the tsv part should be fixed (BTW it's a 
trivial fix [1]), I'm not sure about csv files with xls extension. Users 
shouldn't expect that after changing the file extension to some random 
extension, it still would be recognized as a csv by default. But on the other 
hand the fact that some user opened a bug for it, might indicate that some 
app\web app generates such files. So what do you think? Should it be fixed, or 
should we close the bug as WONTFIX?

The relevant bug reports are:
https://bugs.freedesktop.org/show_bug.cgi?id=68903 (csv with .xls extension)
https://bugs.freedesktop.org/show_bug.cgi?id=69290 (tsv)

Best Regards,
Maxim Monastirsky

(When responding, please be aware that I'm not subscribed to the list)

[1] https://bugs.freedesktop.org/show_bug.cgi?id=68903#c8