bug(formly-form): validateOnModelChange not firing with promise change

[kentcdodds]

@isaac-l noticed that the Matching Two Fields example is broken. After some investigation I found that it works with version 7.1.2, but breaks with version 7.2.0 from this commit by @BarryThePenguin.

@BarryThePenguin, I don't have time right now to look at this, but do you suppose you could give it a look? If not, feel free to assign it back to me. Thanks!

[kentcdodds]

Also, here's a jsbin with the working version. Notice that it references v7.1.2 explicitly.

[kentcdodds]

I think I'll give this one a look.

[kentcdodds]

Here's the original reproduction steps @isaac-l gave the other day

Is there a known issue with http://angular-formly.com/#/example/other/matching-two-fields ? As far as I can tell, it doesn't work as expected
For example:

1. Set email to a@b.c
2. Set confirm to a@b.cd (Causes validation error as expected)
3. Set email to a@b.cd (Should be valid, but still shows a validation error)
   Likewise, setting valid values then changing Email doesn't cause validation to fail

[BarryThePenguin]

Apologies I never responded, haven't had a chance to look into it. Happy to leave this assigned to @kentcdodds

[immortalcy]

While this is working with version 7.1.2 I tried making the changes @BarryThePenguin made to the current version of formly and test it against repeatedSection. It still seems that on repeatedSection version 7.1.2 is not working. So the issue must be something else as well and not only what Barry changed. I am trying to find a work around on this one and keep you posted. @kentcdodds

[nipuna-g]

@immortalcy @kentcdodds

A small thing that I've noted,
The example does validate the field when you enter an extra character(Or delete one)

To reproduce this you can,

1. Set email to a@b.c
2. Set confirm to a@b.cd (Causes validation error as expected)
3. Set email to a@b.cd (Should be valid, but still shows a validation error)
4. Set email to a@b.cdd (Should be invalid, but not shows as now shown as valid)

I faced a similar issue when writing a custom validator. It was due to the model being checked 'before' the key up event occurred (Validation is done before the model is changed).

Unfortunately I'm not at all familiar with the Formly core code base to find the bug.