The 'is_different' utility function was relying on the sequence of
dictionary keys when determining whether the objects are different or
not, which is incorrect, since Python does not guarantee the order of
keys in regular dictionaries.
This was causing the function to report false inequalities after the
Heat Stack is pushed, thus causing murano to re-push the stack even if
it was not modified in between.
The calls of the 'is_different' method were replaced with simple
equality check which are guaranteed to return appropriate result. The
only known limitation of such approach is its inability to check for
circular references. However this is not the case for Murano-generate
Heat snippets, since all the variables in MuranoPL are immutable and
it's impossible to create a circular-referencing snippet with
MuranoPL. Thus it is safe to completely remove 'is_different' method
and all related code.
The same patch also introduces a simple check which verifies that the
HeatStack.update_template() method introduces an actual change into
the template, or does not cause a subsequent push() call otherwise.
Change-Id: Ia71b44ed62f39d9c89630c5a5c21b79c7c17ea9d
Closes-bug: #1594451
55a785afcc