http://lists.gnupg.org/pipermail/gnupg-devel/2009-September/025357.html:
It seems that some GnuPG2 2.0.12 packages do not import old keys
with the deprecated
following algorithms anymore:
2 - RSA Encrypt-Only [HAC] 3 - RSA Sign-Only [HAC]
rfc4880 notes:
Encrypt-Only (2) and RSA Sign-Only are deprecated and SHOULD NOT be generated, but may be interpreted.
For a test case see:
http://lists.wald.intevation.org/pipermail/gpg4win-devel/2009-September/000881.html
http://lists.wald.intevation.org/pipermail/gpg4win-devel/2009-September/000882.html
Gpg1 still does it.
Certainly a defect is that the algorithm is reported as unknown.
Gpg2 should report them as deprecated if I understand Werner correctly:
http://lists.gnupg.org/pipermail/gnupg-devel/2009-September/025364.html