Fixing NMT DDP override that no longer works with PTL 1.2 
thanks @ericharper ! This pull request **introduces 3 alerts** when merging 9dcc1f64b1c17437a1403e44e44ef03cfce3e122 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-70210a020f64159d504b1a88930512edba534cf8)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging dbfa7b3854023ef0910227de56ce26457f036edb into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-6cca4e6f4f304898526462dbd12742b412bde2d5)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 0f411448a03fc5d4515edaf1af3b2f282adef0b8 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-1d886c4d0c8f69a070dbfb8071a77b1c22dfc067)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 9631de965b199109a65c7dc491ca0ddbce21a40c into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-de2cf13324bb7e30b1e222a508c63c509f1104bc)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 182eb34c53839e8f01983b14cdbaec77bb53c4e1 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-61260e6612c74a9efc3f854317ef448854a8be1c)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 86bc8dea2aa33a4025b62284105dfc2b74b44faa into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-1571b280ef8b396e3c8be708ab133621c586a039)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 8644e66856d98be42e51d2cd70dc50593b464037 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-34316b2eaedd7c8bf182799535c6745c7ae97d0f)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging c0099e9d464493ad3ccdd68aeb4fd13f8c163426 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-d3bcf405a97cc818651b03e0a12bd33dc2d6901c)

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* 3 for Unused import This pull request **introduces 3 alerts** when merging 6c488a4ade1d451ff513ab046d2cc53759c5dae2 into 79bef5681e9023287c8a839b3eb5d0bad25dd3eb - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-39a83a00139f45b4f32a32c18c6d5ee3c6bd0a5e)

**new alerts:**

* 3 for Unused import
Also, need to update/add tests that would have caught this problem.