python3-catkin-tools debian uninstallable on bionic due to missing python3-trollius package

I tried to install python3-catkin-tools today on a new bionic machine and it failed to install

$ sudo apt install python3-catkin-tools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 python3-catkin-tools : Depends: python3-trollius but it is not installable
E: Unable to correct problems, you have held broken packages.

I’ve fallen back to the python2 version for now to keep working.

It appears that the python3-trollius package is only available on xenial and not newer: https://packages.ubuntu.com/xenial/python3-trollius

[mikepurvis]

… however, if I hack the trollius/tasks.py file and remove/rename the offending function (on line 565), as well as its listing in the __all__ dunder at the top of the file, then it seems to work as expected.

[mikepurvis]

The one goofy thing I got was as my build was finishing up:

[build] Summary: All 28 packages succeeded!
[build]   Ignored:   2 packages were skipped or are blacklisted.
[build]   Warnings:  None.
[build]   Abandoned: None.
[build]   Failed:    None.
[build] Runtime: 1 minute and 34.0 seconds total.
[build] Note: Workspace packages have changed, please re-source setup files to use them.
Exception ignored in: <function BaseEventLoop.__del__ at 0x7fa8971964d0>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/trollius/base_events.py", line 395, in __del__
  File "/usr/local/lib/python3.7/dist-packages/trollius/unix_events.py", line 65, in close
  File "/usr/local/lib/python3.7/dist-packages/trollius/unix_events.py", line 166, in remove_signal_handler
  File "/usr/lib/python3.7/signal.py", line 47, in signal
TypeError: signal handler must be signal.SIG_IGN, signal.SIG_DFL, or a callable object