properly cache when a branch in a certain revision does not contain a composer.json
properly cache when a branch in a certain revision does not contain a composer.json

this prevents requesting/trying to get the composer.json over and over again even if no commits happend

Closes #7156

staabm/composer,stof/composer,milleruk/composer,localheinz/composer,composer/composer,stefangr/composer,naderman/composer,nicolas-grekas/composer,fabpot/composer,alcohol/composer,johnstevenson/composer,pierredup/composer,slbmeh/composer,floverdevel/composer,vdm-io/composer,andrerom/composer