util._hgexecutable: default to 'hg'
This should make hooks work even if util.set_hgexecutable is not called
(e.g. hgweb.cgi).
Fixes issue625.
#!/bin/sh
# test command parsing and dispatch
hg init a
cd a
echo a > a
hg ci -Ama -d '0 0'
echo "# missing arg"
hg cat
echo '% [defaults]'
hg cat a
cat > $HGRCPATH <<EOF
[defaults]
cat = -v
EOF
hg cat a
echo '% no repo'
cd ..
hg cat
exit 0