make sure metrics/plots can compare dirty repo with the last commit by default

[efiop]

Which versions get compared by default? without sending arguments
I expected the present metrics file to be plotted on top of the last commit but if I manually change this metrics file, the changes are not reflected in the plot.
Only if I run dvc repro in a way that generates a different metrics file does it pick up the changes and plots them.
Where is this version coming from? I haven't committed anything to Git.
On DVC 1.0

https://discordapp.com/channels/485586884165107732/563406153334128681/719342575835676733

[jorgeorpinel]

Sweet, thanks!

It would be great to confirm whether the description currently in treeverse/dvc.org/pull/1382 (hopefully merged soon) is the correct desired behavior.

[efiop]

Yep, can confirm the issue. Preparing a fix right now.