Draft: Un-break ability to open files beginning with something like a URL scheme
Like "Hello: foo.txt". This got broken in ca5e0796.
I added a test case that fails without this change. Unfortunately the change also breaks two existing test cases that were previously succeeding:
absolute-urls-not-in-dirabsolute-urls-not-in-dir-scheme-mixed
I don't feel like I understand this code well enough to fix them. @meven help is appreciated, or just take this over if you prefer.