dir-spec doesn't cover '-legacy' authority entries

Some consensus headers contain "dir-source *-legacy" lines. Here's an example from 2011-10-29-05-00-00-consensus (attached):

[...]
dir-source urras 80550987E1D626E3EBA5E5E75A458DE0626D088C 208.83.223.34 208.83.223.34 443 80
contact 4096R/E012B42D Jacob Appelbaum <jacob@appelbaum.net>
vote-digest C6E35236E655F00EBE1A750C75E38AFF17B56A62
dir-source gabelmoo-legacy 81349FC1F2DBA2C2C11B45CB9706637D480AB913 212.112.245.170 212.112.245.170 80 443
dir-source moria1 D586D18309DED4CD6D57C18FDB97EFA96D330566 128.31.0.34 128.31.0.34 9131 9101
contact 1024D/28988BF5 arma mit edu
vote-digest 3D115F7BA5E0A2C624D32C8C514171C9CE3E790F
[...]

Stem complains:

ParsingFailure: Authority entries must have a 'contact' line:
dir-source gabelmoo-legacy 81349FC1F2DBA2C2C11B45CB9706637D480AB913 212.112.245.170 212.112.245.170 80 443

See dir-spec.txt Section 3.5 for how to handle these lines correctly.