Revert "fetch2/local.py: avoid using PREMIRROR"
This reverts commit e130dca85bac82bd4d88f94a6bf9fe36e8ad4d7c.
This is in fact a valid use case, for example the sstate.bbclass code
sets up SSTATE_MIRRORS as PREMIRRORS. Its quite common to map those
file:// urls to remote http:// urls and with the above change, this
no longer works.