colcon builds "in-source"

edit

Opposed to the documentation provided here colcon build creates the output directories "log", "install" and "build" in place.

Considering I have packages in src the commands roscd <my_fancy_ros_package>; colcon build would create a workspace structure:

workspace
  - src
      - <my_fancy_ros_package>
          - build
          - log
          - install 
          - (other directories contained in <my_fancy_ros_packag> like "msg", "include" …

to have the output directories as peers of "src" I have to change directory up to "workspace" (roscd <my_fancy_ros_package>; cd ../..; colcon build

Are there any (undocumented) options I somehow set to disable out-out-source builds? I have the following colcon packages installed (from bouncy setup instructions as far as I remember)

python3-colcon-argcomplete/bionic,bionic,bionic,bionic,now 0.3.0-1 all [installed,automatic]
python3-colcon-bash/bionic,bionic,bionic,bionic,now 0.3.1-1 all [installed,automatic]
python3-colcon-bazel/bionic,bionic,bionic,bionic 0.1.0-1 all
python3-colcon-cmake/bionic,bionic,bionic,bionic,now 0.2.5-1 all [installed,automatic]
python3-colcon-common-extensions/bionic,bionic,bionic,bionic,now 0.2.0-2 all [installed]
python3-colcon-core/bionic,bionic,bionic,bionic,now 0.3.14-1 all [installed,automatic]
python3-colcon-defaults/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-devtools/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-library-path/bionic,bionic,bionic,bionic,now 0.2.0-1 all [installed,automatic]
python3-colcon-metadata/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-mixin/bionic,bionic,bionic,bionic 0.1.1-1 all
python3-colcon-notification/bionic,bionic,bionic,bionic,now 0.2.5-1 all [installed,automatic]
python3-colcon-output/bionic,bionic,bionic,bionic,now 0.2.3-1 all [installed,automatic]
python3-colcon-package-information/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-package-selection/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-parallel-executor/bionic,bionic,bionic,bionic,now 0.2.2-1 all [installed,automatic]
python3-colcon-pkg-config/bionic,bionic,bionic,bionic,now 0.1.0-1 all [installed,automatic]
python3-colcon-powershell/bionic,bionic,bionic,bionic,now 0.3.3-1 all [installed,automatic]
python3-colcon-python-setup-py/bionic,bionic,bionic,bionic,now 0.2.1-1 all [installed,automatic]
python3-colcon-recursive-crawl/bionic,bionic,bionic,bionic,now 0.2.0-1 all [installed,automatic]
python3-colcon-ros/bionic,bionic,bionic,bionic,now 0.3.6-1 all [installed,automatic]
python3-colcon-test-result/bionic,bionic,bionic,bionic,now 0.3.0-1 all [installed,automatic]
python3-colcon-zsh/bionic,bionic,bionic,bionic,now 0.3.1-1 all [installed,automatic]

this happens with ros2 (bouncy) and ros1 (melodic) workspaces, regardless of which ROS_DISTRO is set