%2fs in urls confuse some mirrors

The string version of the project id (i.e. bazel%2Fape) is supposed to work, except we found out that artifactory's mirror support cannot handle it (it expands the %2F into / before the redirect, which gitlab can't handle). We've filed this as a ticket with jfrog, but I was wondering if you wanted the patch I cut for it. It looks like I can't submit an MR without additional setup, so I've attached the patch here.