The EFI HTTP driver in the TianoCore EDK2 apparently doesn't expect to
deal with more than one file per instance. If asked to do so, it
corrupts memory including TLS pointers, leading to a crash.
Work around this by tearing down the HTTP instance and recreating it
before trying to access a different file.
The upstream bug report is https://bugzilla.tianocore.org/show_bug.cgi?id=1917