g_file_new_for_commandline_arg() doesn't work well when directory has some colon

Submitted by Vincent Untz @vuntz

Link to original bug (#676626)

Description

Try the following:

mkdir foo:bar gedit foo:bar/test

gedit will fail to open the file with a "Could not open the file foo:///bar/test. gedit cannot handle foo: locations." error.

I'm actually unsure if that's something that is fixable, as g_file_new_for_commandline_arg() works like this by design. But for URI schemes that we don't support, this feels wrong.

What we could do is test if foo:bar is an existing directory, but I doubt we want to do some IO in g_file_new_for_commandline_arg().

I've no clue if this is just WONTFIX or if there is a proper solution.

(And yes, I'm aware that this works fine if I use a proper URI for the file, or if I use the full path)