I find
```
 ........E
======================================================================
ERROR: Gray must be a string to distinguish 3-4 grays from RGB or RGBA.
----------------------------------------------------------------------
...
  File ".../lib/matplotlib/tests/test_colors.py", line 206, in test_colors_no_float
...
```
Easier to understand than 
```
........E
======================================================================
ERROR: matplotlib.tests.test_colors.test_colors_no_float
----------------------------------------------------------------------
```

But it's up to you. Will change to comment.