Test metrics is not being reported to TensorBoard since 0.7.2
🐛 Bug

To Reproduce
Steps to reproduce the behavior:
https://colab.research.google.com/drive/1fM6xL140u9pU0vcmJf6qKzHwczjcMpcF

Code sample

Please see the colab above.
Expected behavior

The test metrics should be reported.
Environment
The Colab environment:
cuda:
	GPU:
	available:           False
	version:             10.1
packages:
	numpy:               1.18.2
	pyTorch_debug:       False
	pyTorch_version:     1.4.0
	pytorch-lightning:   0.7.2
	tensorboard:         2.2.0
	tqdm:                4.38.0
system:
	OS:                  Linux
	architecture:
		64bit
		
	processor:           x86_64
	python:              3.6.9
	version:             #1 SMP Wed Feb 19 05:26:34 PST 2020

Additional context
Regression from 0.7.1