prevent (prompt for) auth for bitbucket public downloads
prevent (prompt for) auth for bitbucket public downloads

#5584

yaman-jain/composer,alcohol/composer,hirak/composer,jreinke/composer,johnstevenson/composer,dzuelke/composer,pierredup/composer,andrerom/composer,curry684/composer,erasys/composer,slbmeh/composer,naderman/composer,localheinz/composer,composer/composer,remicollet/composer,SpacePossum/composer,milleruk/composer,fabpot/composer,fabiang/composer,floverdevel/composer,vdm-io/composer,stof/composer,stefangr/composer,till/composer,MoT3rror/composer,staabm/composer,gencer/composer,balbuf/composer,nicolas-grekas/composer