Possible bug with notmuch search & --limit --offset

[jake]

Hello, 

I'm finding that when I use the --limit option with the output=files and
offset=N that the returned list of files is of variable length.

For instance when:

notmuch search --output=files --offset=6 --limit=2 steve

it returns

/var/spool/mail/virtual/archive/sl/.Sent/cur/1335243985.M765351P23366V000000
0000000801I0000000000820E9C_5.archive,S=275069:2,S
/var/spool/mail/virtual/archive/sl/.Sent/cur/1335243986.M749883P23366V000000
0000000801I0000000000820E9D_6.archive,S=275069:2,S
/var/spool/mail/virtual/archive/sl/.Sent/cur/1335243987.M926961P23366V000000
0000000801I0000000000820EA0_9.archive,S=111888:2,S
/var/spool/mail/virtual/archive/sl/.Sent/cur/1335243988.M718230P23366V000000
0000000801I0000000000820EA1_10.archive,S=111888:2,S

Which is two more results than required. If I choose different offset values
then the number of returned results will vary too. 

If I issue:

notmuch search --offset=6 --limit=2 steve

It returns two results as expected, if I change the output type to anything
other than files (summary/threads/messages/tags) then the correctly limited
list is returned. So it only seems to happen with the files output type.
Both json and text format types exhibit the same behaviour.

Am I using this correctly ? I expect only two results to be returned but
being new to notmuch gives me doubts that what I am doing may be incorrect.

My apologies if the mailing list is not the place for this sort of report,
please direct me to a more appropriate place.

Many Thanks
Jake