formatNumber doesn't handle short numbers correctly in some locales

[owencraig]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?

When using a locale such a ta-in which has an lgSize of 3 and a gSize of 2 (i.e.. ##,##,##0) and a number is sent to the filter with a length equal to the lgSize (e.g. 100) then it is being grouped with the gSize.

E.g.
100000 => 1,00,000
1000 => 1,000
100 => 1,00

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://plnkr.co or similar (template: http://plnkr.co/edit/tpl:yBpEi4).

http://plnkr.co/edit/wpJezypsNj7EnatSruKI

What is the expected behavior?

Smaller numbers on the cusp of the lgSize should be formatted as the lgSize e.g in ta-in 100 => 100

What is the motivation / use case for changing the behavior?

Correcting a regression

Which versions of Angular, and which browser / OS are affected by this issue? Did this work in previous versions of Angular? Please also test with the latest stable and snapshot (https://code.angularjs.org/snapshot/) versions.

This affects all browsers and is present in angular 1.4.9 and 1.4.10. It appears to have been introduced by the changes that landed in 9c49eb1

Other information (e.g. stacktraces, related issues, suggestions how to fix)
Pull request incoming