Generate PATH_INFO URLs in the form project/action/hash_base:/filename
rather than project/action/hash_base:filename (the latter form is still
accepted in input).
This minimal change allows relative navigation to work properly when
viewing HTML files in raw ('blob_plain') mode.
Signed-off-by: Giuseppe Bilotta <redacted> Acked-by: Jakub Narebski <redacted> Signed-off-by: Junio C Hamano <redacted>