some APKs do not have a name, like system APKs

some APKs do not have a name, like system APKs

It is not necessarily a good idea to try to distribute system APKs via
FDroid, but `fdroid update` should just ignore APKs it cannot handle rather
than die and prevent a repo from being fully created.  This is necessary to
handle the automatic creation of repos, like for debug builds from a
Jenkins server.