Retrieving a key from a keyserver with gpgme

[Jeroen Ooms]

Here is a simplified version of my binding to retrieve some public
keys from a keyserver:
https://gist.github.com/jeroenooms/29e203d23afd36a3d113. Not sure if
this is the best way of doing this. A few questions:

1) Is there any way I can check if gpg.conf has a keyserver
configured? Or better: can I set a keyserver in gpgme, rather than use
the one from gpg.conf (i.e. the --keyserver param in gpg)

2) Currently the export step fails for some keys. For example: the
first one succeeds, but the second one does not. Why is this?

./lookup 0x7638D0442B90D010e
./lookup 0x924FC6ADC80B5E36

3) After calling gpgme_op_export_keys for the first time, the all
subsequent calls to gpgme_op_keylist_next return GPG_ERR_INV_VALUE.