lei-up doesn't output replies to matching thread

[Josh Steadmon <steadmon@google.com>]

Hello again,

I'm having trouble where `lei up --all` is not outputting threaded
replies, despite the fact that the saved search requests them. I noticed
the problem on this Git thread:
https://lore.kernel.org/git/520da361-1b80-4ba3-87b2-86d6fdfc18b5@web.de/

My saved search is as follows:

{
  "output": "maildir:/usr/local/google/home/steadmon/.mail/lei-git-unit-tests",
  "q": ["(dfn:t/unit-tests OR s:unit OR ((nq:bug OR nq:regression) AND nq:unit)) AND rt:2.weeks.ago.."],
  "external": "1",
  "local": "1",
  "remote": "1",
  "threads": "1"
}

Lei is aware of the replies, because I can see them with lei-q if I copy
the query from the saved search:

$ lei q -t "(dfn:t/unit-tests OR s:unit OR ((nq:bug OR nq:regression) AND nq:unit)) AND rt:2.weeks.ago.." \
  | grep "t-prio-queue: simplify using compound literals" \
  | wc -l
11


In my output maildir, I only have the initial message that started the
thread:

$ cd ~/.mail/lei-git-unit-tests
$ grep -Rl "Subject:.*t-prio-queue: simplify using compound literals" \
  | wc -l
1


And lei-up does not seem to see those matches:

$ lei up ~/.mail/lei-git-unit-tests
# /usr/local/google/home/steadmon/.local/share/lei/store 10/10
# 0 written to /usr/local/google/home/steadmon/.mail/lei-git-unit-tests/ (10 matches)


I have not noticed the problem for other threads, but I am not 100% sure
that it's limited to just this one, either. If you have any advice for
further debugging, I'd appreciate the help.

Thanks!