keyword proposal for bugs blocked by a freeze

[Elijah Newren <newren math utah edu>]

In light of all the bugs I've seen that were help up by a freeze, only
to later be noticed again during another freeze in the following release
cycle, I think we should add a keyword.  I'm not sure of the exact name
for the keyword, or the exact semantics.  So, I'll just throw this
proposal out and ask for feedback.

Note that I would like to have it so that maintainers can and want to
query on this keyword after a thaw.  Thus I would like to avoid it being
applied to too many bugs which might discourage maintainers from
querying on the keyword.  The easiest way to do this is to just say that
only maintainers set the keyword, but I'm guessing that maintainers will
forget and we should probably allow at least some others to set it too.

Proposal for new keyword:
  Keyword name: BLOCKED_BY_FREEZE
  Keyword description: This keyword should be used for bugs for which
    action can be taken by the maintainer once feature/ui/string/code
    freeze is removed, but for which all further actions are blocked
    until that time.  Should be set by maintainers.

Comments?