Private key inconsistent between initial creation and export

When creating a key from the keybase interface you get an option to download the private key and / or upload it to keybase for convenience.

In the event of you saving the private and allow keybase to store it; performing an "Export my private key from Keybase" provides you a similar but different private key. In my experience after a few hundred characters the key begins to change.

I'm no crypto export, but I'd assume these keys should identical.

Further to this, performing a gpg --import of the originally downloaded key (offered on creation) results in:

gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

However attempting an import of the exported key (offered after keybase storage) succeeds.

Reproduce the keybase interface flow: download a private key during creation, allow Keybase to store it, export it later, and run gpg --import on both files. Compare the two outputs and determine whether they should match; done means the intended private-key export is consistent and imports successfully.

Written by the indexing model from the issue text.