How many times after importing a solution with Plugins, we have either errors because of versions, missing steps, the system complaining of something, i think the next few lines will help to understand what happens in the back-end when importing a solution with Plugins (changed code or even less or more steps).
From MSDN https://msdn.microsoft.com/en-us/library/gg309620.aspx
Plug-in assemblies can be versioned using a number format of major.minor.build.revision defined in the Assembly.info file of the Microsoft Visual Studio project. Depending on what part of the assembly version number is changed in a newer solution, the following behavior applies when an existing solution is updated through import.
The build or revision assembly version number is changed.
- This is considered an in-place upgrade. The older version of the assembly is removed when the solution containing the updated assembly is imported. Any pre-existing steps from the older solution are automatically changed to refer to the newer version of the assembly.
- When an updated solution containing the revised assembly is imported, the assembly is considered a completely different assembly than the previous version of that assembly in the existing solution. Plug-in registration steps in the existing solution will continue to refer to the previous version of the assembly. If you want existing plug-in registration steps for the previous assembly to point to the revised assembly, you will need to use the Plug-in Registration tool to manually change the step configuration to refer to the revised assembly type. This should be done before exporting the updated assembly into a solution for later import.
Hope it helps.
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