Bug 1057377 - Return None if original & fallback search terms unsuitable; r=mdoglio
Bug 1057377 - Return None if original & fallback search terms unsuitable; r=mdoglio

Prior to this patch, if we found an initial search term, but that
search term was unsuitable (eg on blacklist) and the whole log line
fallback *also* resulted in an unsuitable search term, then we would
still return the initial search term, rather than None.

vaishalitekale/treeherder,glenn124f/treeherder,avih/treeherder,tojonmz/treeherder,jgraham/treeherder,adusca/treeherder,akhileshpillai/treeherder,sylvestre/treeherder,glenn124f/treeherder,gbrmachado/treeherder,jgraham/treeherder,wlach/treeherder,akhileshpillai/treeherder,glenn124f/treeherder,tojon/treeherder,rail/treeherder,KWierso/treeherder,tojon/treeherder,kapy2010/treeherder,moijes12/treeherder,tojonmz/treeherder,adusca/treeherder,vaishalitekale/treeherder,edmorley/treeherder,parkouss/treeherder,edmorley/treeherder,wlach/treeherder,gbrmachado/treeherder,moijes12/treeherder,akhileshpillai/treeherder,wlach/treeherder,gbrmachado/treeherder,edmorley/treeherder,kapy2010/treeherder,deathping1994/treeherder,tojon/treeherder,parkouss/treeherder,avih/treeherder,moijes12/treeherder,jgraham/treeherder,sylvestre/treeherder,vaishalitekale/treeherder,akhileshpillai/treeherder,avih/treeherder,wlach/treeherder,sylvestre/treeherder,sylvestre/treeherder,jgraham/treeherder,deathping1994/treeherder,tojonmz/treeherder,moijes12/treeherder,gbrmachado/treeherder,rail/treeherder,adusca/treeherder,rail/treeherder,parkouss/treeherder,sylvestre/treeherder,glenn124f/treeherder,kapy2010/treeherder,tojonmz/treeherder,parkouss/treeherder,moijes12/treeherder,parkouss/treeherder,edmorley/treeherder,avih/treeherder,avih/treeherder,tojonmz/treeherder,sylvestre/treeherder,adusca/treeherder,parkouss/treeherder,akhileshpillai/treeherder,wlach/treeherder,glenn124f/treeherder,tojonmz/treeherder,vaishalitekale/treeherder,rail/treeherder,kapy2010/treeherder,deathping1994/treeherder,gbrmachado/treeherder,adusca/treeherder,jgraham/treeherder,moijes12/treeherder,glenn124f/treeherder,KWierso/treeherder,adusca/treeherder,rail/treeherder,akhileshpillai/treeherder,KWierso/treeherder,tojon/treeherder,KWierso/treeherder,deathping1994/treeherder,deathping1994/treeherder,jgraham/treeherder,deathping1994/treeherder,vaishalitekale/treeherder,rail/treeherder,avih/treeherder,gbrmachado/treeherder,vaishalitekale/treeherder,wlach/treeherder,kapy2010/treeherder