BUG #13763: Failed to re-install Posgresql 9.1

The following bug has been logged on the website:

Bug reference:      13763
Logged by:          Thanh Nguyen
Email address:      thanh.nguyen@altametrics.com
PostgreSQL version: 9.1.19
Operating system:   Windows 7 64
Description:

I recently tried to re-install PosgreSQL 9.1 (64). However, the installer
prompted me to enter the previous "Postgres" account password which I
thought I did removed completely from my first install/uninstall. Question
is how to retrieve or reset Postgres account password from previous install?
I don't see any related Postgres instance in \Program Files\Postgres or
\Program Data\Postgres or Registry or \AppData\Roaming