Patchew email reports should trim test output to a sane limit, perhaps 100 KB

[berrange]

In some qemu-devel patches, the test output from patchew can be enourmous. For example

https://patchew.org/QEMU/20200121122433.50803-1-dgilbert@redhat.com/

this resulted in me being sent a 1.2 MB email from patchew which is rather over the top. Only people directly cc'd on the mail received it, because the qemu-devel size limit caused it to be rejected from mailing list delivery. This means most people will never see the test failure.

Patchew should impose a cap on test output, trimming it to say the most recent 100 KB, so that the messages aren't overly huge and at risk of being rejected by mailing lists. If people want to see the full log they can use the web UI

[bonzini]

It is already trimming the content to only the text around errors; that series is quite a special case, because it's so big and because it has a huge amount of new code that doesn't respect the QEMU coding standards. That said yeah, a global limit in mods/email.py should not be hard to add.