compose: docker-compose: pull unauthorized for private registry

While trying to deploy with docker-compose on a Windows system with docker-compose I cannot pull images from a private registry.

$ docker login nexus.company.com:18446
Username (username):
Password:
Login Succeeded

$ docker-compose pull
Pulling memcache (nexus.company.com:18446/custom-memcached:latest)...
Pulling repository nexus.company.com:18446/custom-memcached
ERROR: unauthorized: authentication required

Pulling directly with Docker works as expected:

$ docker pull nexus.company.com:18446/custom-memcached:latest
latest: Pulling from custom-memcached

a3ed95caeb02: Pull complete
da71393503ec: Pull complete
5cd41edb06aa: Pull complete
d7066ba9851d: Pull complete
2bf2935c93e8: Pull complete
039250837ed5: Pull complete
c576cd65c4e9: Pull complete
add8dfd60915: Pull complete
Digest: sha256:3fd27dec38906853c3f700215aaf02986be2e2114f763a5f9c4339f71787e9c5
Status: Downloaded newer image for nexus.company.com:18446/custom-memcached:latest

Versions:

• docker-compose: 1.8.0-rc1
• Docker 1.12.0-rc3
• Docker Toolbox 1.12.0-rc2
• Registry: Nexus Repository Manager 3.0.0-03

$ docker-machine ip
192.168.99.100

$ docker-machine env
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="C:\Users\username\.docker\machine\machines\default"

export DOCKER_MACHINE_NAME="default"
# Run this command to configure your shell:
# eval $("C:\Program Files\Docker Toolbox\docker-machine.exe" env)

$ docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 1
Server Version: 1.12.0-rc3
Storage Driver: aufs
 Root Dir: /mnt/sda1/var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 10
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host null overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 4.4.14-boot2docker
Operating System: Boot2Docker 1.12.0-rc3 (TCL 7.1); HEAD : 8d9ee9f - Sat Jul  2 05:02:44 UTC 2016
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 995.9 MiB
Name: default
ID: XXBH:DI6X:DOYG:D3MW:NIML:X5VG:ZBHX:PUEA:BCHW:JDVB:BYRJ:Y5YR
Docker Root Dir: /mnt/sda1/var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: 13
 Goroutines: 25
 System Time: 2016-07-04T06:52:27.653725638Z
 EventsListeners: 0
Http Proxy: http://proxy.company.com:8080
Https Proxy: http://proxy.company.com:8080
No Proxy: localhost,127.0.0.1,.company.com
Registry: https://index.docker.io/v1/
Labels:
 provider=virtualbox
Insecure Registries:
 127.0.0.0/8

Did I miss something or does docker-compose ignore registry logins?

Thanks for your help.

Stephan