windows/amd64 gitlab-runner 11.11.0 (6c154264) fails

Summary

Each job i give the runner fails with

ERROR: Job failed: build directory needs to be an absolute path

Steps to reproduce

upgraded runner from 11.10.1 to 11.11.0 on windows, with docker and alpine:latest as configured runner + one instance shell + powershell

.gitlab-ci.yml

deploy:productive:
    stage: deploy
    environment:
      name: productive
      url: https://someurl/register
    before_script:
      - apt-get update -qq && apt-get install -y -qq lftp
    dependencies:
      - release:build
    script:
      - lftp -c "set ftp:ssl-allow yes; set ftp:passive-mode true; open -u $FTP_USER_PROD,$FTP_PASS_PROD $FTP_SERVER_PROD; mirror -Rev dist/ ./dist  --ignore-time --parallel=10 --exclude-glob .git* --exclude .git/"
    when: manual
    tags:
      - i
    only:
      - master

Actual behavior

runner quits with an error message

Expected behavior

should work as with previous release

Relevant logs and/or screenshots

job log

[0KRunning with gitlab-runner 11.11.0 (6c154264)
[0;m[0K  on ASDF 3TKyubrG
[0;msection_start:1558433508:prepare_executor
[0Ksection_end:1558433508:prepare_executor
[0K[31;1mERROR: Job failed: build directory needs to be an absolute path
[0;m

Environment description

config.toml contents

concurrent = 1
check_interval = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = "ASDF"
  url = "https://git..."
  token = "...."
  executor = "docker"
  [runners.custom_build_dir]
  [runners.docker]
    tls_verify = false
    image = "alpine:latest"
    privileged = false
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache"]
    shm_size = 0
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]

[[runners]]
  name = "ASDF-powershell"
  url = "https://git..."
  token = ""
  executor = "shell"
  shell = "powershell"
  [runners.custom_build_dir]
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]

Used GitLab Runner version

Running with gitlab-runner 11.11.0 (6c154264)
  on ASDF 3TKyubrG
ERROR: Job failed: build directory needs to be an absolute path