From: David Bremner <david@tethera.net>
Date: Thu, 30 Aug 2018 11:29:15 +0000 (-0300)
Subject: lib: change parent strategy to use In-Reply-To if it looks sane
X-Git-Tag: debian/0.28_rc0-1~20
X-Git-Url: https://git.cworth.org/git?a=commitdiff_plain;h=87934c432c4bee9df09f268a3f05933c59c2caf1;hp=87934c432c4bee9df09f268a3f05933c59c2caf1;p=notmuch

lib: change parent strategy to use In-Reply-To if it looks sane

As reported by Sean Whitton, there are mailers (in particular the
Debian Bug Tracking System) that have sensible In-Reply-To headers,
but un-useful-for-notmuch References (in particular with the BTS, the
oldest reference is last). I looked at a sample of about 200K
messages, and only about 0.5% these had something other than a single
message-id in In-Reply-To. On this basis, if we see a single
message-id in In-Reply-To, consider that as authoritative.
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