Prevent an infinite loop.
Prevent an infinite loop.

Fixes the issue observed in the Google Storage integration tests
from #2462. The problem was introduced in f3e5d11. This only uses
the internal cached value instead of potentially triggering infinite
list bucket calls.

tpodowd/boto,zachmullen/boto,rosmo/boto,ddzialak/boto,disruptek/boto,weka-io/boto,appneta/boto,campenberger/boto,jotes/boto,disruptek/boto,drbild/boto,lra/boto,drbild/boto,jindongh/boto,SaranyaKarthikeyan/boto,darjus-amzn/boto,vijaylbais/boto,varunarya10/boto,alfredodeza/boto,pfhayes/boto,Pretio/boto,shipci/boto,nikhilraog/boto,j-carl/boto,tpodowd/boto,ramitsurana/boto,shaunbrady/boto,clouddocx/boto,janslow/boto,s0enke/boto,alex/boto,dimdung/boto,serviceagility/boto,Asana/boto,nexusz99/boto,nishigori/boto,vishnugonela/boto,rayluo/boto,weebygames/boto,alex/boto,stevenbrichards/boto,kouk/boto,kouk/boto,TiVoMaker/boto,ryansb/boto,khagler/boto,podhmo/boto,bleib1dj/boto,garnaat/boto,ekalosak/boto,yangchaogit/boto,awatts/boto,abridgett/boto,trademob/boto,revmischa/boto,israelbenatar/boto,zzzirk/boto,bryx-inc/boto,felix-d/boto,elainexmas/boto,ocadotechnology/boto,acourtney2015/boto,appneta/boto