Clamp negative rev numbers at zero.
Prior to this change, trying to run "hg log -r -50:" in a repo with
less than 50 changes caused an error. Now that we clamp at zero: no
more error.
#!/bin/sh
# No local source
hg clone a b
echo $?
# No remote source
hg clone http://127.0.0.1:3121/a b
echo $?
rm -rf b # work around bug with http clone
# Inaccessible source
mkdir a
chmod 000 a
hg clone a b
echo $?
# Inaccessible destination
mkdir b
cd b
hg init
hg clone . ../a
echo $?
cd ..
chmod 700 a
rm -rf a b
# Source of wrong type
mkfifo a
hg clone a b
echo $?
rm a
# Default destination, same directory
mkdir q
cd q
hg init
cd ..
hg clone q
true