Chardev logfile is not written (regression between 5.0 and 5.1)

After update from version 5.0 to 5.1, logfile stopped being populated with console output. The file is being created, but remains empty.

Relevant command line options:

-mon chardev=char0
-serial chardev:char0
-chardev socket,host=127.0.0.10,port=2323,server,nowait,telnet,mux=on,id=char0,logfile=/home/jurkiew/.machiner/runs/2020-08-31T21:46:55-0/internal/log


Full command line:

qemu-system-x86_64
-nodefaults
-no-user-config
-snapshot
-enable-kvm
-cpu
host
-nographic
-echr
17
-mon
chardev=char0
-serial
chardev:char0
-rtc
clock=vm
-object
rng-random,filename=/dev/urandom,id=rng0
-device
virtio-rng-pci,rng=rng0,max-bytes=512,period=1000
-name
2020-08-31T21:46:55-0,debug-threads=on
-smp
sockets=1,cores=9,threads=2
-m
251G
-overcommit
cpu-pm=on
-pidfile
/home/jurkiew/.machiner/runs/2020-08-31T21:46:55-0/internal/pid
-net
nic,model=virtio
-net
user,hostfwd=tcp:127.0.0.10:2222-:22,hostfwd=tcp:127.0.0.10:8000-:8000,hostfwd=tcp:127.0.0.10:9000-:9000
-fsdev
local,id=machiner_internal_dir,security_model=none,path=/home/jurkiew/.machiner/runs/2020-08-31T21:46:55-0/internal
-device
virtio-9p-pci,fsdev=machiner_internal_dir,mount_tag=machiner_internal_dir
-fsdev
local,id=machiner_lower_dir,security_model=none,readonly,path=.
-device
virtio-9p-pci,fsdev=machiner_lower_dir,mount_tag=machiner_lower_dir
-fsdev
local,id=machiner_upper_dir,security_model=mapped-xattr,fmode=0777,dmode=0777,path=/home/jurkiew/.machiner/runs/2020-08-31T21:46:55-0
-device
virtio-9p-pci,fsdev=machiner_upper_dir,mount_tag=machiner_upper_dir
-device
virtio-scsi
-drive
if=none,file=/home/jurkiew/.machiner/images/famtar/image.qcow2,discard=on,id=famtar
-device
scsi-hd,drive=famtar
-chardev
socket,host=127.0.0.10,port=2323,server,nowait,telnet,mux=on,id=char0,logfile=/home/jurkiew/.machiner/runs/2020-08-31T21:46:55-0/internal/log