Implement proposal 275: don't put "published" times in md consensus

When a new consensus method is negotiated, these values will all get
replaced with "2038-01-01 00:00:00".

This change should be safe because:

  * As of 0.2.9.11 / 0.3.0.7 / 0.3.1.1-alpha, Tor takes no action
    about published_on times in the future.

  * The only remaining parties relying on published_on values are (we
    believe) relays running 0.3.5.x, which rely on the values in a NS
    consensus to see whether their descriptors are out of date.  But
    this patch only changes microdesc consensuses.

  * The latest Tor no longer looks at this field in consensuses.

Why make this change?  In experiments, replacing these values with a
fixed value made the size of compressed consensus diffs much much
smaller.  (Like, by over 50%!)

Implements proposal 275; Implements #40130.

0 files changed, 0 insertions, 0 deletions