I've just been working around it by changing the regex, but:

Invalid version format (dotted-decimal versions require at least three parts) at ./admin/InitDb.pl line 68.

(my version string: "PostgreSQL 9.2beta2 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.7.0 20120505 (prerelease), 64-bit" )

Since it's matching against

/PostgreSQL ([0-9\.]*) .*/

... it's choking on 'beta2'.