Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Patches for 5.2.0-rc2:

- quorum: Fix crash with rewrite-corrupted and without read-write user
- io_uring: do not use pointer after free
- file-posix: Use fallback path for -EBUSY from FALLOC_FL_PUNCH_HOLE
- iotests: Fix failure on Python 3.9 due to use of a deprecated function
- char-stdio: Fix QMP default for 'signal'

# gpg: Signature made Tue 17 Nov 2020 11:43:17 GMT
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  iotests/081: Test rewrite-corrupted without WRITE
  iotests/081: Filter image format after testdir
  quorum: Require WRITE perm with rewrite-corrupted
  io_uring: do not use pointer after free
  file-posix: allow -EBUSY errors during write zeros on raw block devices
  iotests: Replace deprecated ConfigParser.readfp()
  char-stdio: Fix QMP default for 'signal'

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>