fix(storage): avoid segmentation fault when generating actions

[joseivanlopez]

Problem

The generation of the storage actions was fixed to avoid a segmentation fault while accessing to the CompoundAction objects, see #1410. But there is still a chance to reference to an actiongraph removed by the ruby GC.

target_graph.actiongraph.compound_actions.map do |action|
  GC.start
  Action.new(a)
end

The actiongraph object could be dropped by the garbage collector while iterating the list of compound actions.

Solution

Keep a reference to the actiongraph, ensuring the actiongraph object is not removed while generating the list of actions.

Note: once the list of actions is generated, the actiongraph is not needed anymore because the Action objects do not keep a reference to the source compound action, see #1410.

[coveralls]

coverage: 71.406%. remained the same
when pulling 5a0ebfb on fix-actions-generator
into 55b6728 on master.

[coveralls]

coverage: 71.406%. remained the same
when pulling 5a0ebfb on fix-actions-generator
into 55b6728 on master.

[ancorgs]

LGTM