docker cp with bash process substitution does not copy the content of the file

Description

I would like to be able to use bash process substitution with docker cp :

docker cp <(echo "hello world") nginx:/hello
docker exec -ti nginx cat /hello

And see "hello world"

Describe the results you received:

cat: /hello: No such file or directory

Describe the results you expected:

See "hello world"

Additional information you deem important (e.g. issue happens only occasionally):

Most commands support process substitution like this, for example :

cp <(echo "hello") hello
cat <(echo hello)

Output of docker version:

$ docker version
Client:
 Version:           18.09.7
 API version:       1.39
 Go version:        go1.10.1
 Git commit:        2d0083d
 Built:             Fri Aug 16 14:20:06 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.09.7
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.1
  Git commit:       2d0083d
  Built:            Wed Aug 14 19:41:23 2019
  OS/Arch:          linux/amd64
  Experimental:     false

Output of docker info:

Containers: 37
 Running: 31
 Paused: 0
 Stopped: 6
Images: 1057
Server Version: 18.09.7
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version:
runc version: N/A
init version: v0.18.0 (expected: fec3683b971d9c3ef73f284f176672c44b448662)
Security Options:
 apparmor
 seccomp
  Profile: default
Kernel Version: 4.15.0-65-generic
Operating System: Ubuntu 18.04.2 LTS
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 15.42GiB
Name: edgar
ID: P2Z2:LWW2:2LF3:DDHP:E2CR:K57E:73RD:GNR6:PH6Y:UQBT:VAI2:HRGO
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Username: ehippaltair
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

WARNING: No swap limit support

Start by reproducing the documented docker cp <(echo "hello world") nginx:/hello command and inspect the docker cp CLI path handling process-substitution input. Done means the command copies the generated content into the container so that docker exec -ti nginx cat /hello prints "hello world".