tests/test-merge3

Modify commands.walk to yield a 4-tuple.
The new element of the tuple indicates whether a name is an exact match
for one passed in on the command line.

#!/bin/sh

hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "0 0"
touch b
hg add b
rm b
hg commit -A -m"comment #1" -d "0 0"