t1410: fix breakage on case-insensitive filesystems

On Sat, Nov 08, 2014 at 08:43:54PM -0500, Jeff King wrote:

> Unfortunately I don't have an OS X install handy to test on.

I lied; it turns out I still had access to an old VM. The problem did
turn out to be rather silly. Here's a patch.

-- >8 --
Two tests recently added to t1410 create branches "a" and
"a/b" to test d/f conflicts on reflogs. Earlier, unrelated
tests in that script create the path "A/B" in the working
tree.  There's no conflict on a case-sensitive filesystem,
but on a case-insensitive one, "git log" will complain that
"a/b" is both a revision and a working tree path.

We could fix this by using a "--" to disambiguate, but we
are probably better off using names that are less confusing
to make it more clear that they are unrelated to the working
tree files.  This patch turns "a/b" into "one/two".

Reported-by: Michael Blume <blume.mike@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>