Symbiosis: common: postinst needs to check for a better valid hostname
Imported from https://www.github.com/BytemarkHosting/symbiosis/issues/57
The HOSTNAME env variable doesn't tend to bell It should probably check against a regexp for the presence of a dot in the $HOSTNAME env variable:
/^[_a-z0-9-]+\.([_a-z0-9-]+\.?)+$/would do the trick