Fixes issue in devserver introduced in v3.3
Fixes issue in devserver introduced in v3.3

Fixes an intermittent devserver problem with directory urls
containing index.html (i.e. clean urls).  It tries to send the
index.html file twice, resulting in a scrambled web page complete
with HTTP headers in the output, and sometimes Broken Pipe errors.

joetboole/pelican,51itclub/pelican,karlcow/pelican,simonjj/pelican,jvehent/pelican,rbarraud/pelican,eevee/pelican,zackw/pelican,number5/pelican,ingwinlu/pelican,11craft/pelican,btnpushnmunky/pelican,JeremyMorgan/pelican,UdeskDeveloper/pelican,TC01/pelican,avaris/pelican,iurisilvio/pelican,jimperio/pelican,karlcow/pelican,koobs/pelican,rbarraud/pelican,iKevinY/pelican,Scheirle/pelican,sunzhongwei/pelican,gymglish/pelican,catdog2/pelican,treyhunner/pelican,jimperio/pelican,deved69/pelican-1,levanhien8/pelican,janaurka/git-debug-presentiation,douglaskastle/pelican,zackw/pelican,JeremyMorgan/pelican,ehashman/pelican,crmackay/pelican,jo-tham/pelican,farseerfc/pelican,lazycoder-ru/pelican,deanishe/pelican,sunzhongwei/pelican,number5/pelican,ls2uper/pelican,deved69/pelican-1,joetboole/pelican,lucasplus/pelican,ls2uper/pelican,abrahamvarricatt/pelican,UdeskDeveloper/pelican,janaurka/git-debug-presentiation,kernc/pelican,simonjj/pelican,catdog2/pelican,talha131/pelican,zackw/pelican,UdeskDeveloper/pelican,gymglish/pelican,abrahamvarricatt/pelican,deanishe/pelican,levanhien8/pelican,Polyconseil/pelican,crmackay/pelican,sunzhongwei/pelican,garbas/pelican,florianjacob/pelican,btnpushnmunky/pelican,Rogdham/pelican,justinmayer/pelican,goerz/pelican,ehashman/pelican,alexras/pelican,11craft/pelican,iurisilvio/pelican,garbas/pelican,abrahamvarricatt/pelican,getpelican/pelican,kennethlyn/pelican,levanhien8/pelican,jimperio/pelican,karlcow/pelican,deved69/pelican-1,lucasplus/pelican,farseerfc/pelican,ehashman/pelican,Summonee/pelican,simonjj/pelican,alexras/pelican,GiovanniMoretti/pelican,goerz/pelican,douglaskastle/pelican,11craft/pelican,rbarraud/pelican,GiovanniMoretti/pelican,51itclub/pelican,HyperGroups/pelican,janaurka/git-debug-presentiation,kernc/pelican,Summonee/pelican,0xMF/pelican,jvehent/pelican,iKevinY/pelican,lucasplus/pelican,talha131/pelican,lazycoder-ru/pelican,Scheirle/pelican,douglaskastle/pelican,avaris/pelican,number5/pelican,getpelican/pelican,alexras/pelican,sunzhongwei/pelican,kernc/pelican,Rogdham/pelican,arty-name/pelican,florianjacob/pelican,koobs/pelican,kennethlyn/pelican,Polyconseil/pelican,jvehent/pelican,HyperGroups/pelican,Rogdham/pelican,btnpushnmunky/pelican,51itclub/pelican,goerz/pelican,treyhunner/pelican,gymglish/pelican,TC01/pelican,GiovanniMoretti/pelican,kennethlyn/pelican,iurisilvio/pelican,ingwinlu/pelican,lazycoder-ru/pelican,Scheirle/pelican,crmackay/pelican,TC01/pelican,JeremyMorgan/pelican,catdog2/pelican,jo-tham/pelican,florianjacob/pelican,treyhunner/pelican,Summonee/pelican,HyperGroups/pelican,ls2uper/pelican,deanishe/pelican,garbas/pelican,koobs/pelican,eevee/pelican,eevee/pelican,joetboole/pelican