gnumach-dbg software package provides Dummy transition package for gnumach-image-*-dbg, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnumach-dbg
gnumach-dbg is installed in your system.
Make ensure the gnumach-dbg package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnumach-dbg *
You will get with gnumach-dbg package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Debug packages |
| Package | gnumach-dbg |
| Version | 2:1.7+git20160921-1 |
| Description | Dummy transition package for gnumach-image-*-dbg |
| Sub Section | debug |