[FIX] owrocanalysis: Fix test for non empty points array

[ales-erjavec]

Issue

ROC Analysis raises

---------------------------- ValueError Exception -----------------------------
Traceback (most recent call last):
  File "/Users/aleserjavec/Documents/workspace/orange3/Orange/widgets/evaluate/owrocanalysis.py", line 674, in _on_mouse_moved
    if pts:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
-------------------------------------------------------------------------------

on mouse hover when two (or more) hovered threshold points are close to each other in viewport.

E.g on Ionospere with logistic regression:

run the mouse cursor over the curve on a small sized ROC Analysis plot.

Description of changes

• Fix test for non empty points array

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #5571 (9df9755) into master (79ac616) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5571   +/-   ##
=======================================
  Coverage   85.90%   85.91%           
=======================================
  Files         313      313           
  Lines       65353    65352    -1     
=======================================
+ Hits        56143    56145    +2     
+ Misses       9210     9207    -3