mjhjmtu

I have two packages A and B where B is an optional component that depends on package A and its exact version. Therefore I need to enure that if both packages are installed they are of the same version. To make it a little bit more complicated installation of package A can fail from the preinst script. In this case nothing should be upgraded

So if A and B are installed the desired behavior should be:

1. 
   dpkg --install A-new.deb
   
   upgrade denied (since B is depending on A)


2. 
   dpkg --install B-new.deb
   
   upgrade denied (since A needs to be upgraded first)


3. 
   dpkg --install A-new.deb B-new.deb
   
   A and B upgraded


4. 
   dpkg --install A-new.deb B-new.deb and upgrading A fails
   
   Nothing changed (i.e. old version of A and B in Installed state)

What I tried:

Adding A (with version) to B's Depends: line in the control file

1. 
   dpkg --install A-new.deb
   
   A is upgraded, B remains the old version


2. 
   dpkg --install B-new.deb
   
   B is upgraded but in Unpacked state, configuring denied due to the dependency


3. 
   dpkg --install A-new.deb B-new.deb
   
   A and B are upgraded


4. 
   dpkg --install A-new.deb B-new.deb and upgrading A fails
   
   A stays at the old version, B is new version in Unpacked state

So only 3. matches the desired behavior

Adding A (with version) to B's Pre-Depends: line in the control file

1. 
   dpkg --install A-new.deb
   
   A is upgraded, B stays at the old version


2. 
   dpkg --install B-new.deb
   
   upgrade denied due to the dependency


3. 
   dpkg --install A-new.deb B-new.deb
   
   A is upgraded, B stays at the old version due to a pre-dependency problem


4. 
   dpkg --install A-new.deb B-new.deb and upgrading A fails
   
   Nothing changed (i.e. old version of A and B in Installed state)

Here only 2. and 4. match the desired behavior

How can I get the desired behavior?