Set unit=1 if anomalies are standardized

[bascrezee]

Closes #726. @hb326 Can you test in combination with the MPQB framework?

[bascrezee]

@hb326 Can you test?

[jvegreg]

Can you please modify the tests in tests/unit/preprocessor/_time/test_time.py#1015 to account for this change?

[bascrezee]

@hb326 Did you test? I can already tell that we run into a few issues that have to be solved. See the linked issue.

[hb326]

@bascrezee: I did test it just now. Does not work for the MPQB.
See the following error message:
ValueError: Unable to convert from 'Unit('1')' to 'Unit('kg m-2 s-1')'.
2020-08-06 09:41:58,509 UTC [44220] INFO If you suspect this is a bug or need help, please open an issue on https://github.com/ESMValGroup/ESMValTool/issues and attach the run/recipe_*.yml and run/main_log_debug.txt files from the output directory.

Seems to me it is the same error as you reported in #741

[hb326]

I ran the MPQB recipe again, with the inlcuded changes to the preprocessor.
Good news: it ran through!
Not so good news: I am missing the units at the y-axis... Are there supposed to be units?

[bascrezee]

Can you check the units of the preprocessor output? ncdump -h I would expect them to be 1.

[hb326]

Can you check the units of the preprocessor output? ncdump -h I would expect them to be 1.

@bascrezee: yes, the unit is 1 in the preprocessor output.

[bascrezee]

Good. Than all is fine I would say, the units not being shown at the y-axis there is Iris behaviour (iris.quickplot.plot). Apparently it defaults to not showing in this case, which is fine. I am now working on the tests as requested by @jvegasbsc.

[bascrezee]

Can this be merged?