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 a
cd a
echo a > foo
hg add foo
hg commit -m 1 -d "0 0"
rm foo
hg remove foo
hg commit -m 2 -d "0 0"

cd ..
hg clone a b