This is actually failing before it gets as far as Launchpad. Apache's mod_proxy_http is throwing away the request, something like this (this is from a local development installation, but I verified this against Apache logs from our "dogfood" site):
[Tue Jun 19 20:15:28.820917 2018] [proxy_http:error] [pid 774:tid 3958287168] (70007)The timeout specified has expired: [client 10.36.63.1:56998] AH01095: prefetch request body failed to 127.0.0.1:8086 (localhost) from 10.36.63.1 (), referer: https://bugs.launchpad.dev/redfish/+bug/15/+addcomment
It looks like, when AppArmor prevents reading an attachment, Firefox sends request headers with a non-zero Content-Length, but then fails to actually follow up by sending that amount of content. Launchpad can't work around this, because as I mentioned it fails (non-configurably) at the Apache stage before it gets to the webapp.
I think the only place this can be fixed is in Firefox.
This is actually failing before it gets as far as Launchpad. Apache's mod_proxy_http is throwing away the request, something like this (this is from a local development installation, but I verified this against Apache logs from our "dogfood" site):
[Tue Jun 19 20:15:28.820917 2018] [proxy_http:error] [pid 774:tid 3958287168] (70007)The timeout specified has expired: [client 10.36.63.1:56998] AH01095: prefetch request body failed to 127.0.0.1:8086 (localhost) from 10.36.63.1 (), referer: https:/ /bugs.launchpad .dev/redfish/ +bug/15/ +addcomment
It looks like, when AppArmor prevents reading an attachment, Firefox sends request headers with a non-zero Content-Length, but then fails to actually follow up by sending that amount of content. Launchpad can't work around this, because as I mentioned it fails (non-configurably) at the Apache stage before it gets to the webapp.
I think the only place this can be fixed is in Firefox.