I don't understand what you are doing here. First you say it can't be null. But then you say this fix allows people to store nulls. This code just feels very very wrong to me.

I will try to explain it better. :)
If I would like to store data using JTable, and I would like to store NULL in my columns, I will use $row->store(true).
Some developers do not use JModelAdmin->save() and JTable->save(). They use JTable->store for that reason.
Here you are an example how I only use store(), not save().

There is no problem with JModelAdmin. I just gave it as example where you can test what will happen when perform $table->store with TRUE as parameter.

If you perform $table->store(true) on line 1181 it will catch the error on line 1196. Look at the second screenshot.

To prevent this error, I will have to put $table->store(true) in try-catch.
The problem is the object $asset on line 846.
The object $asset has property 'alias'.
If the parameter $updateNulls is TRUE ($asset->store(true)), the object tries to store NULL value of its property 'alias' in table '#__assets'.
However, there is no column 'alias' in '#__assets'. Furthermore, there are no columns where you will be able to store NULL values in '#__assets'. So, the property $updateNulls on line 846 is redundant.
If you remove it, that will fix this issue and developers will be able to use $table->store(true) without try-catch. :)

should this PR be tested?

It should be tested and merged.
That will be a solution for the mentioned problem.
https://groups.google.com/forum/#!topic/joomla-dev-general/KZFM8yKZYpg
http://forum.joomla.org/viewtopic.php?f=615&t=775779

You can test it easy. Just add "true" as parameter of $table->store() on line 1181.

That will occur the error that you can see on the second screenshot above.
That happens when we use $table->store(true) to store entities by our extensions. It only happens when we use ACL roles in our extensions. It seems, JTable creates asset records when we use roles for our entities.

That is really strange bug, difficult for detecting because it only occurs when someone use $table->store(true) in extensions with implemented ACL roles. :)

However, it is easy for fixing. You have to remove the redundant $updateNulls on line 846 .

I have tested this item ? unsuccessfully on e8d62b2

• Changed the default value of $updateNulls to true on line 318 in file libraries/legacy/table/content.php.
• Saved an existing Article
• with and without Patch no Error is shown, Article is saved.

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  _{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/10097.}

I told you, it is hard to catch the error. :) You can save an article but the error still exists.

I did a video that shows you how to test with an article.
The second video shows the result when we use $table->store(true) with assets in our extensions.

My arguments for removing $updateNulls on line 846 in file libraries/joomla/table/table.php are:

1. There is no reason to give $updateNulls to $asset->store() on line 846, because the table #__assets does not contain any columns where you can store NULL values.
2. That will be a solution for our problems and we will be able to use $table->store(true) in our projects.

Test with an article
https://www.youtube.com/watch?v=86mlgxa4CxY

Result in our extensions when we use $table->store(true) with assets.
https://www.youtube.com/watch?v=dLtXo9UBsro

@wilsonge does this last explanation answer your question Or should this be closed.

Closing this as it is going nowhere