Fix buglet introduced in r855.
Fix buglet introduced in r855.

* context.c
  (read_from_connection): return APR_SUCCESS in the case where we're exhausted.

yesoce/serf,TommyU/serf,google-code-export/serf,TommyU/serf,justinweb/serf,KyleSanderson/serf,muthusuba/serf,lazysoez/serf,x-clone/serf,soufianeEL/serf,muthusuba/serf,liuzongquan/serf,yesoce/serf,alex1818/serf,soufianeEL/serf,pengdu/serf,justinweb/serf,blueszhangsh/serf,Manouchehri/serf,krime/serf,yesoce/serf,soufianeEL/serf,wzugang/serf,zhupan/serf,TommyU/serf,blueszhangsh/serf,muthusuba/serf,SirJson/serf,justinweb/serf,blueszhangsh/serf,lazysoez/serf,Manouchehri/serf,x-clone/serf,x-clone/serf,yesoce/serf,blueszhangsh/serf,idomon/serf,Manouchehri/serf,idomon/serf,stoneCC/serf,wzugang/serf,google-code-export/serf,Manouchehri/serf,soufianeEL/serf,sworda/serf,zhupan/serf,lazysoez/serf,idomon/serf,sworda/serf,zhupan/serf,stoneCC/serf,liuzongquan/serf,idomon/serf,pengdu/serf,zhengcq315/serf,sworda/serf,google-code-export/serf,wzugang/serf,KyleSanderson/serf,lazysoez/serf,TommyU/serf,stoneCC/serf,krime/serf,alex1818/serf,pengdu/serf,alex1818/serf,zhupan/serf,KyleSanderson/serf,KyleSanderson/serf,liuzongquan/serf,liuzongquan/serf,zhengcq315/serf,google-code-export/serf,zhengcq315/serf,zhengcq315/serf,SirJson/serf,justinweb/serf,pengdu/serf,krime/serf,wzugang/serf,stoneCC/serf,alex1818/serf,x-clone/serf,SirJson/serf,muthusuba/serf,krime/serf,SirJson/serf,sworda/serf