upload: Fix exception uploaded files with unknown content type.
upload: Fix exception uploaded files with unknown content type.

It turns out our detected content_type can actually be None, which
meant calling force_text on it broke uploading some files.

blaze225/zulip,Juanvulcano/zulip,souravbadami/zulip,jrowan/zulip,christi3k/zulip,souravbadami/zulip,mohsenSy/zulip,timabbott/zulip,vikas-parashar/zulip,niftynei/zulip,eeshangarg/zulip,niftynei/zulip,Jianchun1/zulip,AZtheAsian/zulip,eeshangarg/zulip,jphilipsen05/zulip,sup95/zulip,showell/zulip,dattatreya303/zulip,arpith/zulip,calvinleenyc/zulip,Juanvulcano/zulip,grave-w-grave/zulip,niftynei/zulip,sharmaeklavya2/zulip,sharmaeklavya2/zulip,Diptanshu8/zulip,ahmadassaf/zulip,andersk/zulip,shubhamdhama/zulip,sharmaeklavya2/zulip,ryanbackman/zulip,showell/zulip,umkay/zulip,vaidap/zulip,AZtheAsian/zulip,paxapy/zulip,shubhamdhama/zulip,umkay/zulip,brainwane/zulip,j831/zulip,synicalsyntax/zulip,jainayush975/zulip,zacps/zulip,christi3k/zulip,dawran6/zulip,vaidap/zulip,mahim97/zulip,TigorC/zulip,amyliu345/zulip,SmartPeople/zulip,verma-varsha/zulip,zacps/zulip,aakash-cr7/zulip,amyliu345/zulip,cosmicAsymmetry/zulip,ahmadassaf/zulip,KingxBanana/zulip,PhilSk/zulip,Galexrt/zulip,rishig/zulip,rishig/zulip,jackrzhang/zulip,jphilipsen05/zulip,samatdav/zulip,niftynei/zulip,krtkmj/zulip,vabs22/zulip,sup95/zulip,grave-w-grave/zulip,PhilSk/zulip,isht3/zulip,SmartPeople/zulip,mohsenSy/zulip,reyha/zulip,tommyip/zulip,tommyip/zulip,paxapy/zulip,krtkmj/zulip,sup95/zulip,krtkmj/zulip,Galexrt/zulip,AZtheAsian/zulip,Juanvulcano/zulip,cosmicAsymmetry/zulip,arpith/zulip,punchagan/zulip,mahim97/zulip,Juanvulcano/zulip,AZtheAsian/zulip,tommyip/zulip,brockwhittaker/zulip,tommyip/zulip,niftynei/zulip,timabbott/zulip,mahim97/zulip,vikas-parashar/zulip,KingxBanana/zulip,j831/zulip,shubhamdhama/zulip,ahmadassaf/zulip,vabs22/zulip,rht/zulip,hackerkid/zulip,amanharitsh123/zulip,brainwane/zulip,tommyip/zulip,vikas-parashar/zulip,showell/zulip,mohsenSy/zulip,kou/zulip,kou/zulip,SmartPeople/zulip,rht/zulip,zulip/zulip,brockwhittaker/zulip,brockwhittaker/zulip,dawran6/zulip,krtkmj/zulip,dattatreya303/zulip,jackrzhang/zulip,synicalsyntax/zulip,krtkmj/zulip,zacps/zulip,eeshangarg/zulip,showell/zulip,amanharitsh123/zulip,sup95/zulip,calvinleenyc/zulip,dattatreya303/zulip,ryanbackman/zulip,blaze225/zulip,SmartPeople/zulip,christi3k/zulip,rishig/zulip,Galexrt/zulip,jphilipsen05/zulip,andersk/zulip,dhcrzf/zulip,punchagan/zulip,JPJPJPOPOP/zulip,grave-w-grave/zulip,timabbott/zulip,blaze225/zulip,kou/zulip,hackerkid/zulip,susansls/zulip,cosmicAsymmetry/zulip,Jianchun1/zulip,arpith/zulip,amyliu345/zulip,jainayush975/zulip,showell/zulip,amanharitsh123/zulip,Jianchun1/zulip,punchagan/zulip,jainayush975/zulip,umkay/zulip,amanharitsh123/zulip,shubhamdhama/zulip,arpith/zulip,JPJPJPOPOP/zulip,JPJPJPOPOP/zulip,ahmadassaf/zulip,zulip/zulip,j831/zulip,vabs22/zulip,Diptanshu8/zulip,SmartPeople/zulip,rishig/zulip,samatdav/zulip,dawran6/zulip,dhcrzf/zulip,PhilSk/zulip,dhcrzf/zulip,grave-w-grave/zulip,zulip/zulip,zacps/zulip,souravbadami/zulip,jackrzhang/zulip,verma-varsha/zulip,sonali0901/zulip,AZtheAsian/zulip,TigorC/zulip,hackerkid/zulip,samatdav/zulip,synicalsyntax/zulip,KingxBanana/zulip,souravbadami/zulip,vabs22/zulip,TigorC/zulip,dhcrzf/zulip,verma-varsha/zulip,j831/zulip,peguin40/zulip,Juanvulcano/zulip,zulip/zulip,j831/zulip,krtkmj/zulip,vikas-parashar/zulip,dawran6/zulip,zacps/zulip,christi3k/zulip,amanharitsh123/zulip,christi3k/zulip,cosmicAsymmetry/zulip,joyhchen/zulip,sharmaeklavya2/zulip,aakash-cr7/zulip,sonali0901/zulip,andersk/zulip,andersk/zulip,JPJPJPOPOP/zulip,Galexrt/zulip,blaze225/zulip,punchagan/zulip,vaidap/zulip,brainwane/zulip,rishig/zulip,andersk/zulip,jphilipsen05/zulip,brainwane/zulip,sup95/zulip,hackerkid/zulip,synicalsyntax/zulip,sup95/zulip,KingxBanana/zulip,Jianchun1/zulip,jrowan/zulip,timabbott/zulip,tommyip/zulip,arpith/zulip,hackerkid/zulip,eeshangarg/zulip,synicalsyntax/zulip,tommyip/zulip,rishig/zulip,kou/zulip,grave-w-grave/zulip,shubhamdhama/zulip,reyha/zulip,samatdav/zulip,rht/zulip,timabbott/zulip,souravbadami/zulip,Diptanshu8/zulip,amyliu345/zulip,punchagan/zulip,Diptanshu8/zulip,Diptanshu8/zulip,KingxBanana/zulip,hackerkid/zulip,shubhamdhama/zulip,AZtheAsian/zulip,dawran6/zulip,shubhamdhama/zulip,joyhchen/zulip,sonali0901/zulip,calvinleenyc/zulip,ryanbackman/zulip,kou/zulip,dhcrzf/zulip,brainwane/zulip,eeshangarg/zulip,synicalsyntax/zulip,Jianchun1/zulip,dattatreya303/zulip,amyliu345/zulip,susansls/zulip,showell/zulip,krtkmj/zulip,rishig/zulip,cosmicAsymmetry/zulip,aakash-cr7/zulip,sharmaeklavya2/zulip,paxapy/zulip,Jianchun1/zulip,umkay/zulip,vabs22/zulip,paxapy/zulip,synicalsyntax/zulip,arpith/zulip,dhcrzf/zulip,rht/zulip,brockwhittaker/zulip,Galexrt/zulip,vaidap/zulip,rht/zulip,SmartPeople/zulip,jackrzhang/zulip,ryanbackman/zulip,jackrzhang/zulip,paxapy/zulip,umkay/zulip,niftynei/zulip,PhilSk/zulip,brockwhittaker/zulip,zulip/zulip,Galexrt/zulip,susansls/zulip,jainayush975/zulip,mohsenSy/zulip,vabs22/zulip,peguin40/zulip,kou/zulip,aakash-cr7/zulip,verma-varsha/zulip,jrowan/zulip,jainayush975/zulip,christi3k/zulip,peguin40/zulip,andersk/zulip,calvinleenyc/zulip,reyha/zulip,dawran6/zulip,susansls/zulip,ahmadassaf/zulip,Juanvulcano/zulip,calvinleenyc/zulip,peguin40/zulip,brainwane/zulip,rht/zulip,amanharitsh123/zulip,PhilSk/zulip,aakash-cr7/zulip,joyhchen/zulip,isht3/zulip,eeshangarg/zulip,umkay/zulip,calvinleenyc/zulip,peguin40/zulip,verma-varsha/zulip,kou/zulip,zulip/zulip,rht/zulip,timabbott/zulip,cosmicAsymmetry/zulip,vikas-parashar/zulip,ahmadassaf/zulip,aakash-cr7/zulip,dattatreya303/zulip,jackrzhang/zulip,isht3/zulip,jrowan/zulip,vaidap/zulip,andersk/zulip,KingxBanana/zulip,showell/zulip,jainayush975/zulip,susansls/zulip,Diptanshu8/zulip,blaze225/zulip,susansls/zulip,ahmadassaf/zulip,vikas-parashar/zulip,umkay/zulip,j831/zulip,samatdav/zulip,sonali0901/zulip,reyha/zulip,brockwhittaker/zulip,sonali0901/zulip,jphilipsen05/zulip,joyhchen/zulip,zulip/zulip,mahim97/zulip,vaidap/zulip,jrowan/zulip,mahim97/zulip,reyha/zulip,verma-varsha/zulip,Galexrt/zulip,amyliu345/zulip,grave-w-grave/zulip,jrowan/zulip,timabbott/zulip,hackerkid/zulip,dhcrzf/zulip,jackrzhang/zulip,sharmaeklavya2/zulip,isht3/zulip,dattatreya303/zulip,punchagan/zulip,zacps/zulip,punchagan/zulip,brainwane/zulip,jphilipsen05/zulip,PhilSk/zulip,mohsenSy/zulip,TigorC/zulip,JPJPJPOPOP/zulip,sonali0901/zulip,ryanbackman/zulip,isht3/zulip,JPJPJPOPOP/zulip,eeshangarg/zulip,reyha/zulip,ryanbackman/zulip,isht3/zulip,blaze225/zulip,mohsenSy/zulip,paxapy/zulip,mahim97/zulip,joyhchen/zulip,souravbadami/zulip,samatdav/zulip,peguin40/zulip,TigorC/zulip,joyhchen/zulip,TigorC/zulip