I'm trying to use a filter "+*foo=*[0-9]*" to match what the regex
".*foo=[0-9].*" matches, but for some reason it seems like it also matches
things like "...foo=x123...". Now, of course I could instead write "+*foo=0*
+*foo=1* +*foo=2* ...", but is there some other way of matching only URLs
containing "foo=<somenumber>"?