Error when value is an URL with an = symbol
I don't believe that this is a general problem with the "template" format. Did you try running the same query with, say, the "table" format, to see if the same problem happens there (i.e., the issue is actually with the storing of the data)? If the problem is unique to the "template" format, could you include the relevant portion of your template, that displays the URL?
Page with ask that uses this template: http://wiki.15m.cc/wiki/Lista_de_noticias
You can see the broken external links in some of the rows. All are cases of URLs with '?='.
Could the issue be that you need to a "1=" to the "convertir fecha" template call in that 2nd link?