Some URLs cannot be converted via URL.toURI(). So don't convert
the full URL but only the bits that are needed to find a proxy
via java.net.ProxySelector.
Bug: 549690
Change-Id: I55b5ecee70c6b52f72f9bdba9ce552fde7f33976
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>