yaml-mode installs but gives error

[Andre]

On `stretch` I am getting a spurious error when `install`ing and `purge`ing `yaml-mode`. The mode is actually installed and `emacs` will highlight `yaml` files correctly. I could find no references in Debian bugs.

```bash
$ sudo apt-get install yaml-mode
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  yaml-mode
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/10.5 kB of archives.
After this operation, 26.6 kB of additional disk space will be used.
Selecting previously unselected package yaml-mode.
(Reading database ... 130962 files and directories currently installed.)
Preparing to unpack .../yaml-mode_0.0.9-2_all.deb ...
Unpacking yaml-mode (0.0.9-2) ...
Setting up yaml-mode (0.0.9-2) ...
ERROR: yaml-mode is broken - called emacs-package-install as a new-style add-on, but has no compat file.
Install emacsen-common for emacs24
emacsen-common: Handling install of emacsen flavor emacs24
Wrote /etc/emacs24/site-start.d/00debian-vars.elc
Wrote /usr/share/emacs24/site-lisp/debian-startup.elc
Install yaml-mode for emacs
Install yaml-mode for emacs24
install/yaml-mode: Handling install for emacsen flavor emacs24
Loading 00debian-vars...
Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...
Info: Skip debian-el loading if run under dpkg control.
Loading /etc/emacs/site-start.d/50yaml-mode.el (source)...
Wrote /usr/share/emacs24/site-lisp/yaml-mode/yaml-mode.elc
$ sudo apt-get purge yaml-mode
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  yaml-mode*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 26.6 kB disk space will be freed.
Do you want to continue? [Y/n]
(Reading database ... 130972 files and directories currently installed.)
Removing yaml-mode (0.0.9-2) ...
ERROR: yaml-mode is broken - called emacs-package-remove as a new-style add-on, but has no compat file.
Remove yaml-mode for emacs24
remove/yaml-mode: purging byte-compiled files for emacs24
(Reading database ... 130963 files and directories currently installed.)
Purging configuration files for yaml-mode (0.0.9-2) ...
```

Dependencies:
```bash
$ apt-cache depends yaml-mode
yaml-mode
 |Depends: emacs
  Depends: <emacsen>
    emacs24
    emacs24-lucid
    emacs24-nox
    emacs25
    emacs25-lucid
    emacs25-nox
    xemacs21-mule
    xemacs21-mule-canna-wnn
    xemacs21-nomule
  Depends: emacsen-common
$ dpkg -l | grep emacs
ii emacs 46.1 all GNU Emacs editor (metapackage)
ii emacs24 24.5+1-11+deb9u1 armhf GNU Emacs editor (with GTK+ GUI support)
ii emacs24-bin-common 24.5+1-11+deb9u1 armhf GNU Emacs editor's shared, architecture dependent files
ii emacs24-common 24.5+1-11+deb9u1 all GNU Emacs editor's shared, architecture independent infrastructure
ii emacs24-el 24.5+1-11+deb9u1 all GNU Emacs LISP (.el) files
ii emacsen-common 2.0.8 all Common facilities for all emacsen
ii yaml-mode 0.0.9-2 all emacs mode for YAML files
```