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
hg init test
cd test
echo % Without -v
hg serve -a localhost -p 20063 -d --pid-file=hg.pid
cat hg.pid >> "$DAEMON_PIDS"
echo % With -v
hg serve -a localhost -p 20064 -d --pid-file=hg.pid -v
cat hg.pid >> "$DAEMON_PIDS"