Homebrew/homebrew-versions — pull request #1 by lotia (2012-03-23 12:23:46+00:00)
Title: Change postgres9 datadir location.

The postgresql 9 data directory is changed from #{var}/postgres
to #{var}/postgres9.

This change certainly does not provide the capability for multiple
versions to run concurrently, but it does provide some measures to
prevent data from being accidentally overwritten or converted to
a new version.