Avoid crash when aborting POST from the server side.
Avoid crash when aborting POST from the server side.

Reported by Tero Pelander.

darcs-hash:20070823045722-4cc09-79a4a689a1a1d8d3a2cbc8dfc18bfa282e39aa62.gz

jeromelebel/polipo,galeksandrp/polipo,berkley4/polipo,ssb22/polipo2,Android-Apps/polipo,akkakks/polipo,akkakks/polipo,strongwillow/polipo,strongwillow/polipo,doublec/namecoin-polipo,galeksandrp/polipo,jech/polipo,fqtools/polipo,nxtreaming/chumen,clowwindy/polipo,Psiphon-Inc/polipo,toke/polipo,fukusaka/polipo,ssb22/polipo2,berkley4/polipo,fqtools/polipo,feijilei/polipo,caeies/polipo-caeies,akkakks/polipo,dxq-git/polipo,lkraider/polipo,lkraider/polipo,lkraider/polipo,nxtreaming/chumen,jech/polipo,feijilei/polipo,feijilei/polipo,dxq-git/polipo,danchr/polipo,Android-Apps/polipo,nxtreaming/chumen,jech/polipo,galeksandrp/polipo,gorakhargosh/polipo,TierraDelFuego/opilop,dxq-git/polipo,fqtools/polipo,ajmgh/polipo,berkley4/polipo,ssb22/polipo2