Integration with rules / loop causes front page to be expired incorrectly

This is a fairly complicated issue:

using rules integration, i'm looping over all the values of a list item in a field and clearing all the urls that have that field value at the end:

e.g. a field called: field_stuff with values stuff_1, stuff_2, stuff_3

and anytime a node is changed with field_stuff, i'm looping over that field and clearing every page that is page-to-clear/stuff_1, page-to-clear/stuff_2... etc.

what i'm seeing is that this works, but ALSO the front page's cache is getting cleared on every content change (which i am not asking it to do)

i checked in the expire settings, and the front page is NOT checked to expire.

i've dug into the rules module extensively and figured out that it seems to be an issue with this module in the expire.rules.inc file:

when the urls are exploded in line 42, an extra array element is created with a blank space (' ') value. when expire loops through those urls, it ends up clearing the front page, when it should not in this case. adding an explicit check for this value and doing nothing if its caught fixes this issue.