[wix-devs] Defining "forward-compatible bundle"

[Joseph Musser]

I am really sorry for all the questions! I'm sure any one of you could tell
me a line or two to change to fix the BA same version upgrade bug. Rob said
<https://twitter.com/wixtoolset/status/836809637961875457> this bug can't
really be painful because no one has stepped up to contribute a fix;
however, it's continuing to cause enough pain and wasted time where I work
that I'm determined to learn how to fix it since I know you're all busy.

I've searched the internet and the wix3 documentation and haven't been able
to find info on these:

DetectForwardCompatibleBundle
<https://github.com/wixtoolset/wix3/blob/a83b2130299ef95c9b0ec5c6d80bf34cc4722dfb/src/burn/engine/detect.cpp#L82>:
What are forward-compatible bundles? Why might a custom BA want to handle
OnDetectForwardCompatibleBundle?

DetectReportRelatedBundles
<https://github.com/wixtoolset/wix3/blob/a83b2130299ef95c9b0ec5c6d80bf34cc4722dfb/src/burn/engine/detect.cpp#L146>:
What kinds of things can end up being related bundles? Why might a custom
BA want to handle OnDetectRelatedBundle?

Is DetermineRelationType
<https://github.com/wixtoolset/wix3/blob/a83b2130299ef95c9b0ec5c6d80bf34cc4722dfb/src/burn/engine/relatedbundle.cpp#L136>
likely the place where the same version upgrade fix needs to start?

Thanks so much!