dirstate._dirs: fix refcounting broken by 7dfac37cfabf
reported by Patrick Waugh
#!/bin/sh
mkdir r1
cd r1
hg init
mkdir a
echo foo > a/f
hg add a
hg ci -m "a/f == foo"
cd ..
hg clone r1 r2
cd r2
hg mv a b
echo foo1 > b/f
hg ci -m" a -> b, b/f == foo1"
cd ..
cd r1
mkdir a/aa
echo bar > a/aa/g
hg add a/aa
hg ci -m "a/aa/g"
hg pull ../r2
hg merge
hg st -C