bug#13306: clarification

[Mark Lillibridge <mdl@alum.mit.edu>]

    In case it wasn't clear from the last message, occurs does not work
sanely with Rmail buffers currently even in version 24.2.  It takes you
to the occurrence point but there is no way to narrow the buffer so you
can do things like forward the found message.

    Perhaps a way to narrow a widened Rmail buffer around point would be
a useful independent function.  I'm wondering if such a function called
from the right occurs mode hook (assuming it exists) would suffice to
provide the functionality I'm asking for here.

- Mark
PS, note that both grep and the proposed occurs search the raw mbox file
not the results of decoding the messages; if someone wanted to go for
extra awesomeness, they might try and make an special Rmail search
command that produces an occurs buffer but only searches the decoded
messages (e.g., ignore nontext parts, work on base 64/printable
representations correctly).  This would be substantially slower, but
would avoid a lot of false positives.