Mutiple edits to draft isn't syncronised to IMAP (gmail)

Expected behavior

Performing multiple editing sessions on a draft message in K9 should synchronise all changes to IMAP, allowing to start a message in K9 while on mobile to continue and finish it using an IMAP desktop client.

Actual behavior

The first draft saved from K9 is synchronised to IMAP, subsequent changes done using and present in K9 draft folder are not synchronised, the draft on IMAP remains the first saved.

Nothing I have attempted can trigger a message synchronisation, I have had IMAP drafts sitting stale for weeks; forcing K9 synchronisation, restarting K9, rebooting phone, resynchronising IMAP client. The remedy I resort to is either sending the mail to myself, or creating a new draft with copy-pasted contents.

This used to work but I have experienced this consistently since a recent K9 update (I remember upgrading from a release dated Nov 2019).

Steps to reproduce

1. First edit; Write new mail with some contents (body=“Body”, subject=“Subject”), see screenshot 1
2. Save as draft (back->Save as draft or menu->Save as draft), see screenshot 2
3. Second edit; Reopen draft message, write some more text (“Additional body”), see screenshot 3
4. Save as draft (back->Save as draft or menu->Save as draft), see screenshot 4
5. Observe that only the first edit of the message is present in IMAP folder (fx. Thunderbird IMAP client or gmail.com web interface), see screenshots 5 & 6

Environment

• K-9 Mail version: 5.717, see screenshot 7
• Android version: 7.0, see screenshot 8
• Account type (IMAP, POP3, WebDAV/Exchange): IMAP (gmail)
• Phone model: Samsung Galaxy S8, SM-G950F

Screenshots

Done using Danish (dansk) locale. Quick parlour;

• skrive = write
• fra = from
• til = to
• kladder = drafts

1 - first edit

1 - saved first edit

3 - second edit

4 - saved second edit

5 - IMAP Thunderbird

6 - IMAP gmail web interface

7 - K9 version

8 - Android version

Log

Please take some time to retrieve logs and attach them here: k9-log_redacted.txt

This was redacted from the plain log using: sed -e s/example.com/"<redcated domain>"/g -e s/user/"<redacted user name>"/g k9-log.txt >k9-log_redacted.txt

First edit start: 2020-07-08T19:59:55+02:00 Second edit end: ~2020-07-08T20:02:00+02:00 Activity thereafter shows another unrelated draft being composed (for screenshots transfer).

[cketti]

I removed some code that I believed was unused. Turns out it was a very quirky mechanism that made replacing drafts on the server work. I’m not going to restore that code. Instead we’ll do it “the right way”. This is part of a larger effort and will take some time to complete.

[manne01]

Just to confirm, it works since 5.724 - great work, thank you so much!