The scheme property returns 'file://' for local paths instead of 'file', causing scheme_plus_authority to produce 'file://://' with a triple slash.
Also fix the test to expect 'file' instead of 'file://'.
Assisted-by: unsloth/Qwen3.6-35B-A3B-GGUF:IQ4_NL with pi.dev v0.80.2
Signed-off-by: Jan Lindemann <jan@janware.com>