Split make_file back out into make_filename and make_file.
It turns out that make_filename is useful by itself.
#!/bin/bash
set -x
mkdir a
cd a
hg init
echo a > a
hg add a
hg commit -t test -u test -d '0 0'
# Default operation
hg clone . ../b
cd ../b
cat a
hg verify
# No update
hg clone -U . ../c
cd ../c
cat a
hg verify
# Default destination
mkdir ../d
cd ../d
hg clone ../a
cd a
hg cat a