fixed the hanging bug of text classification model.
This pull request **introduces 1 alert** when merging 0a42bc5c87cce6e6bcbe1ccff4772a6caca25a9c into 17fc2541172dd3d781bfa0b5a1fa41576d4bfe21 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-25e2feefaf1a084c11c7c502283923afe3fa5df8)

**new alerts:**

* 1 for Unused import
Dropped the evaluation with another trainer in the same script.