Describe the bug
When uploading a large file in Releases (after raising the default limit), the upload times out with the error message:

[ERROR] [reflect/value.go:460 call()] parse multipart form: multipart: NextPart: stream error: stream ID 39; CANCEL

or, in a similar vein:

[reflect/value.go:460 call()] parse multipart form: multipart: NextPart: stream error: stream ID 81; CANCEL

Gogs version and commit
Build time: 2020-05-04 10:53:31 UTC
Build commit: 9fd4f55

Git version

2.24.3

Operating system
Ubuntu 16.04 LTS (docker gogs/gogs:latest)

Database
postgres 9.5 (docker)

To Reproduce
Steps to reproduce the behavior:

1. Raise release file size limit.
2. Upload at least a 1.5GB+ file as a Release in a repo.
3. Wait for it to timeout.

Can you reproduce the bug at https://try.gogs.io?
No, cannot upload file that large.

Expected behavior
I expect Gogs to complete the file upload and not time out.

Actual behavior
Gogs will time out, produce the error code above, and not allow the download to continue.

Screenshots

Additional context

2020/05/06 13:23:42 [ INFO] Run mode: Production
2020/05/06 13:23:43 [ INFO] Listen on https://0.0.0.0:3000
2020/05/06 13:24:29 [ERROR] [reflect/value.go:460 call()] parse multipart form: multipart: NextPart: stream error: stream ID 39; CANCEL
2020/05/06 13:28:01 [ERROR] [reflect/value.go:460 call()] parse multipart form: multipart: NextPart: stream error: stream ID 81; CANCEL

I've tried both Chrome and Firefox. Uploading from Windows Server 2016.