prepends "/?=undefined&" in url, removes all filters and redirect to "?e=1"

[peppelinux]

If I set a datetime or a date filter as frst selection

/?creation_date__gte=2017-03-08+00%3A00%3A00%2B01%3A00&creation_date__lt=2017-03-16+00%3A00%3A00%2B01%3A00

then if I select a dal admin filters of mine the new window location is:

/?=undefined&creation_date__gte=15%2F03%2F2017&creation_date__lte=15%2F03%2F2017&tipo_marketing=3

the erroneous "/?=undefined&" drive the window location in a new url with "?e=1" and all the previosly selected filters removed.

This happens only if a datetime filter preceeds a dal filter, if other sequence of filter appended in url this bug will not be raised.

Actually tested on two different Django platforms

[peppelinux]

Th bug appears when in the url, in window.location.search, the date filters contains hours and minutes notation lke the previouse examples or a & as prefix, like this example:

?&creation_date__gte=16%2F03%2F2017&creation_date__lte=16%2F03%2F2017

The previous bug disappears if the window.location.search is like this:
/?creation_date__gte=2017-03-08&creation_date__lt=2017-03-16

I fixed this bug in js file querystring.js, at line 48, this way:

  for (var i = 0; i < q.length; i++) {
    
    // prevents undfined "?e=1" redirects
    if (q[i].length < 1) { continue; }