I'm asking for clarification. Is my following understanding correct?

What I'm seeing is as in the title. On my very example,

• Ubuntu 18.04
• python-rosdep (not python3)
• Ran rosdep install against a pkg that has python3-inputimeout-pip key. A pkg inputimeout seems installed via pip but python3 failed to import that.

If this is expected, it makes sense from developer's perspective. It's just confusing from an operator's point of view.

Just as a proof, take python3-inputimeout-pip rosdep key as an example, here's a proof for what I'm seeing.

$ docker run -it ros:melodic-ros-base bash

root@52f5cb8c7b45:/# apt-cache policy python-rosdep              
python-rosdep:                                                       
  Installed: 0.21.0-1                                           
  Candidate: 0.21.0-1                                                       

root@52f5cb8c7b45:/# apt-cache policy python3-rosdep                                                                                                            
python3-rosdep:                                                                                                                                                                                                                                                                                                               
  Installed: (none)                                               
  Candidate: (none)                                                                                                                                                                                                                                                                                                           
root@52f5cb8c7b45:/# mkdir -p /cws/src && cd /cws/src && catkin_create_pkg testes python3-inputimeout-pip

root@52f5cb8c7b45:/cws# cat src/testes/package.xml |grep -i depend
:
  <build_depend>python3-inputimeout-pip</build_depend>
  <build_export_depend>python3-inputimeout-pip</build_export_depend>
  <exec_depend>python3-inputimeout-pip</exec_depend>

root@52f5cb8c7b45:/cws/src# cd .. && apt update && rosdep update && apt install -y python-pip && rosdep install -r -y --from-paths src --ignore-src


executing command [pip2 install -U inputimeout]            
Collecting inputimeout
  Downloading https://files.pythonhosted.org/packages/b3/57/420f8181c31c87eab5815af006ea7c6053e965465d9f52ddf4078ffd7c4a/inputimeout-0.1.1.tar.gz
Building wheels for collected packages: inputimeout
  Running setup.py bdist_wheel for inputimeout ... done
  Stored in directory: /root/.cache/pip/wheels/17/6d/cf/e12a540e76cbcbe9b112ddf1a8fc43a9fb74f623f4f3b75962
Successfully built inputimeout                                                                                                                                                                                                                                                                                                
root@52f5cb8c7b45:/cws# python --version                    
Python 2.7.17                                                                                                                                                  
root@52f5cb8c7b45:/cws# python -c "from inputimeout import inputimeout, TimeoutOccurred"
root@52f5cb8c7b45:/cws# 

root@52f5cb8c7b45:/cws# python3 -c "from inputimeout import inputimeout, TimeoutOccurred"                                                                       
Traceback (most recent call last):                      
  File "<string>", line 1, in <module>                  
ModuleNotFoundError: No module named 'inputimeout'