Correct optimization from 3464f5e77f34; add a test.
If there are two (or more) heads that point to the same .hgtags
node, we can safely skip parsing the file in all but the last head.
(In 3464f5e77f34, we were parsing the file in the first head and
skipping all the others.)
#!/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