Description of problem:
I tried to download the public key for Ken Coar, and got a very confusing error message.  I then logged in as a different user, and tried again, and it succeeded.  The import filter is over-active, and appears to be refusing to import a key solely because an 8-digit identifier associated with the key happens to have a substring that matches the username associated with my own personal key.

Version-Release number of selected component (if applicable):
gnupg-1.4.18-1.fc20.x86_64


How reproducible:
100% for me, but not for all users


Steps to Reproduce:
1. Create a personal gpg key associated with a short all-hex username.  In my case, although my $USER of eblake is non-hex, my key happens to be associated with a secondary email address ebb9: gpg --fingerprint eblake
2. Try to download another public subkey where the associated master key has the same all-hex substring: gpg --recv-keys f46d6ac2
3. Try to inspect the key: gpg --fingerprint 0xf46d6ac2
4. As a work-around, import the subkey directly: gpg --fingerprint 0xf46d6ac2
5. Now try to inspect it: gpg --fingerprint 0xf46d6ac2
6. Log on as a different user: su -l dummy; echo $USER
7. Try again to download: gpg --recv-keys f46d6ac2

Actual results:
1. $ gpg --fingerprint eblake
pub   2048R/2527436A 2010-04-16
      Key fingerprint = 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A
uid                  Eric Blake <eblake>
uid                  Eric Blake (Free Software Programmer) <ebb9>
uid                  [jpeg image of size 6874]
sub   2048R/D2E4726C 2010-04-16

2. $ gpg --recv-keys f46d6ac2
gpg: requesting key F46D6AC2 from hkp server keys.gnupg.net
gpg: key 4EBB96FF: rejected by import filter
gpg: Total number processed: 1

3. $ gpg --fingerprint 0xf46d6ac2
gpg: error reading key: public key not found

4. $ gpg --recv-keys 4ebb96ff 
gpg: requesting key 4EBB96FF from hkp server keys.gnupg.net
gpg: key 4EBB96FF: public key "Ken Coar (Open sourcerer) <coar>" imported
gpg: 3 marginal(s) needed, 1 complete(s) needed, classic trust model
gpg: depth: 0  valid:   1  signed:   6  trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1  valid:   6  signed:  46  trust: 0-, 4q, 0n, 0m, 2f, 0u
gpg: depth: 2  valid:  41  signed:  29  trust: 1-, 1q, 0n, 28m, 11f, 0u
gpg: depth: 3  valid:  10  signed:  21  trust: 0-, 6q, 0n, 1m, 3f, 0u
gpg: depth: 4  valid:   4  signed:   9  trust: 2-, 1q, 0n, 0m, 1f, 0u
gpg: next trustdb check due at 2015-01-29
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

5. $ gpg --fingerprint 0xf46d6ac2
pub   4096R/4EBB96FF 1997-01-24
      Key fingerprint = 4333 9E61 30A2 CA74 206F  8653 5ADF 9B5C 4EBB 96FF
uid                  Ken Coar (Open sourcerer) <coar>
uid                  Ken Coar (Open sourcerer, PHP hacker) <coar>
uid                  Ken Coar (Open sourcerer, opinionist) <Ken>
uid                  Ken Coar (Open sourcerer, Perl hacker) <ROUS>
uid                  Ken Coar (Open methodology evangelist) <coar>
uid                  Ken Coar (Opinionist [eddress retired]) <Ken.Coar>
uid                  Ken Coar/Rodent of Unusual Size (Born 1960-04, Florida, USA)
uid                  Ken Coar (Opinionist [eddress retired]) <Ken.Coar>
uid                  Ken Coar (Open sourcerer, systems rationaliser) <coar>
uid                  Ken Coar (Open sourcerer, systems rationaliser) <kcoar>
uid                  Ken Coar (Open sourcerer, systems rationaliser) <genghisken>
uid                  Ken Coar (Open sourcerer, opinionist, fallback eddress) <Ken.Coar>
sub   2048R/5D5F76E9 1997-01-24
sub   1024D/31F752F3 2014-07-22 [expires: 2016-07-21]
sub   4096R/F46D6AC2 2014-07-22 [expires: 2016-07-21]

6. echo $USER
dummy

7. $ gpg --recv-keys f46d6ac2
gpg: requesting key F46D6AC2 from hkp server keys.gnupg.net
gpg: key 4EBB96FF: public key "Ken Coar (Open sourcerer) <coar>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)


Expected results:

At step 2, the input filter should not have prevented me from getting the key.  I should not have had to resort to either step 4 (change my download request) or 7 (log on as a different user)

Additional info: