title: Matplotlib Quiver plot matching key label color with arrow color
body: <p>Using matplotlib, python3.6. I am trying to create some quiverkeys for a quiver plot but having a hard time getting the label colors to match certain arrows. Below is a simplified version of the code to show the issue.  When I use the same color (0.3, 0.1, 0.2, 1.0 ) for a vector at (1,1) and as 'labelcolor' of a quiverkey I see 2 different colors. </p>
  
  <pre><code>q=plt.quiver([1, 2,], [1, 1],
               [[49],[49]],
               [0],
               [[(0.6, 0.8, 0.5, 1.0 )],
               [(0.3, 0.1, 0.2, 1.0 )]],
               angles=[[45],[90]])
  plt.quiverkey(q, .5, .5, 7, r'vector2', labelcolor=(0.3, 0.1, .2, 1),
                labelpos='S', coordinates = 'figure')
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/BYCoj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BYCoj.png" alt="enter image description here"></a></p>