Comment 5 for bug 1786986

Basically what xdg-open does with $BROWSER is to set it if and only if
it's unset. If it's set, it should be a colon separated list of
possibilities, starting with x-www-browser. Instead, in our case, it's
equal to qupzilla only. That said, something outside of xdg-open is
setting it to qupzilla, so it's not xdg-open.

It's also not falkon. I was thinking maybe there were some remaining
references left in the postinst to qupzilla, but it is not the case. If
BROWSER was unset, it would be set to x-www-browser and the postinst of
falkon does set it as x-www-browser, so we'd be done.

Unfortunately, it's already set. So maybe that's a bug against xdg-open
that it doesn't do anything if it's already set, but I don't think so.

That said, your hint was a good one, as it gets to the heart of the
problem (the value of BROWSER) but the solution is not obvious. We could
add a BROWSER setting to falkon's postinst but that would really be sort
of strange. None of firefox, chromium-browser, konqueror, epiphany or
w3m do this. I think it would be better if we find the cause and remove
it.