Git bug - Windows subst/net use, Windows drive letter prefix

I believe there is a subtle bug in Git that can mean that a "git add" fails, complaining that "fatal: <filename>: '<filename>' is outside repository at '//<server>/<share>/<directory> /'

It may be possible to reproduce this with simpler steps, but this is what I have that fails.

1. A Git repo on system <server> below directory <directory> that can be reached via the Windows share <share>
2. On a second system, perform "net use z: file://%3cserver%3e/%3cshare>"
3. Now you can "cd /d z:\<directory>" and run "git status" quite happily 
4. At this point I can also so this:
	a. "cd /d z:" then "git add <z:\some-changed-file>"
		i. Note the drive letter prefixing the full-filename
5. Now do a subst or a net use as follows:
	a. subst v: z:\directory
	b. net use w: file://%3cserver%3e/%3cshare%3e/%3cdirectory>
6. You can do both of these
	a. "cd /d v:" then "git status"
	b. "cd /d w:" then "git status"
7. However both of these FAIL:
	a. "cd /d v:" then "git add <v:\some-changed-file>"
	b. "cd /d w:" then "git add <w:\some-changed-file>"
		i. Note the drive letter prefixing the full-filename
8. Performing the above requests WITHOUT the drive letter prefixing the filename works!

I assume that this is supposed to work and there is some subtle error merging the repository root and the filename-with-drive-prefix.

Regards, Paul D.Smith.