BUG: diff_instances fails if workdir_old != workdir_new

[mihaTrajbaric]

Function opera.commands.diff.diff_instances( storage_old, workdir_old, storage_new, workdir_new,...) should be able to calculate difference between two instance states in two different workdirs.

This fails because of this two function calls:

# inside diff_instances(...)
 template_old = get_template(storage_old)
 template_new = get_template(storage_new)

and implementation of function opera.utils.get_template(storage)

# inside get_template(...)
 ast = tosca.load(Path.cwd(), PurePath(service_template))

which works only, if Path.cwd() == workdir_old == workdir_new

[anzoman]

@mihaTrajbaric thanks for bringing this up! I believe that this issue was known about when we released the first version of opera that included opera diff and opera update, knowing that we will have to resolve this in the future. Maybe @alexmaslenn can provide more info on how to fix this bug efficiently.

[anzoman]

Fixed with #195.