If it helps providing more failure scenarios, I can't sign the Tails
signing key from Tails 2.2:
<pre>
Preparing to sign with this key
pub [unknown] 4096R/30F80A2C 1287394206 [expiry: 1500995439]
Fingerprint = DF84 1752 B55C D97F DA48 79B2 9E5B 04F4 30F8 0A2C
uid 1 [unknown] sajolida <sajol...@pimienta.org>
sub 4096R/34AD5681 1287394206
Signing the following key
pub [unknown] 4096R/58ACD84F 1421590671 [expiry: 1484145775]
Fingerprint = A490 D0F4 D311 A415 3E2B B7CA DBB8 02B2 58AC D84F
uid 1 [unknown] Tails developers (offline long-term identity key)
<ta...@boum.org>
uid 2 [unknown] Tails developers <ta...@boum.org>
sub 4096R/752A3DB6 1421590835 [expiry: 1484147888]
sub 4096R/56987A65 1421590930 [expiry: 1452522130]
sub 4096R/2F699C56 1421595116 [expiry: 1484147927]
Sign all identities? [y/N] y
Really sign key? [y/N] y
cannot select uid for signing: [GNUPG:] KEYEXPIRED 1452522130
</pre>
