convert: svn -- fix 'exists' Previously 'exists' erroneously returned False for empty dirictories. This is wrong since we want to detect even empty 'branches/' or 'tags/'.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
hg history
hg manifest --debug
hg cat a
hg verify