BUG #10087: Invalid Apt GPG key

The following bug has been logged on the website:

Bug reference:      10087
Logged by:          Alex Shafer
Email address:      ashafer01@gmail.com
PostgreSQL version: 9.3.0
Operating system:   Debian 7.0
Description:

% wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc |
sudo apt-key add -
OK

% sudo apt-get update
...
W: A error occurred during the signature verification. The repository is not
updated and the previous index files will be used. GPG error:
http://apt.postgresql.org wheezy-pgdg Release: The following signatures were
invalid: KEYEXPIRED 1381654177

W: Failed to fetch
http://apt.postgresql.org/pub/repos/apt/dists/wheezy-pgdg/Release