Here is the latter half of the output of --card-status in it's entirety...

The URL is listed, as for the signature key, that is the crux of the
problem... it shouldn't care about what the fingerprint of the signature key
when retrieving the public key when the signature key is a subkey as you
can't retrieve just the public key of the subkey, you need to retrieve the
public key of the master key that contains that subkey.

Note below how key 757C0180 is the master key and in the error message in
the op it is looking for AEB99527 which is the signing subkey.

Name of cardholder: John Tennyson
Language prefs ...: en
Sex ..............: male
URL of public key :
https://gist.githubusercontent.com/aelana/0cde322d66206ea5fb90/raw/1cc31e99f
bdb5a75e4104fe597794ec3dccd6bc4/gistfile1.txt
Login data .......: elfindreams
Signature PIN ....: forced
Key attributes ...: 2048R 2048R 2048R
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: 85D5 A0DA 4EC2 B038 128F 9D88 4791 2162 AEB9 9527

created ....: 2015-02-03 21:18:19

Encryption key....: 3AD4 1BA6 47B9 1AA3 89CD C29E A6CF 5D5D CADC 0F35

created ....: 2015-02-03 21:18:48

Authentication key: D61E 29B6 9784 15A9 CEFE 08F4 6AD2 1E6C C40C A003

created ....: 2015-02-03 21:19:08

General key info..: pub 2048R/AEB99527 2015-02-03 Elvish Wanderer
<aelana@elfindreams.com>
sec# 4096R/757C0180 created: 2015-02-03 expires: 2015-11-30
ssb> 2048R/AEB99527 created: 2015-02-03 expires: 2015-11-30

card-no: 0006 03362156

ssb> 2048R/CADC0F35 created: 2015-02-03 expires: 2015-11-30

card-no: 0006 03362156

ssb> 2048R/C40CA003 created: 2015-02-03 expires: 2015-11-30

card-no: 0006 03362156