In 'pyplot.streamplot', starting points near the same streamline raise 'InvalidIndexError'

[galaunay]

Choosing two starting points in the same streamline in pyplot.streamplot lead to
an InvalidIndexError.

Minimal non-working example :

import numpy as np
import matplotlib.pyplot as plt

# Data
x = np.linspace(-10, 10, 10)
y = np.linspace(-10, 10, 10)
X, Y = np.meshgrid(x, y)
U = X*0 + 1
V = X*0
start_points = np.array([[0, 0], [5, 0]])

# streamline plot with aligned starting points
plt.figure()
sp = plt.streamplot(x, y, U, V, start_points=start_points,
                    color='r')
plt.show()

Maybe a better behaviour would be to skip the points responsible for the conflicts, i.e replacing in streamplot.py (in get_integrator(), integrate()):
dmap.start_trajectory(x0, y0)
by

try:
    dmap.start_trajectory(x0, y0)
except InvalidIndexError:
    return None

[tacaswell]

That on the surfaces seems reasonable to me. Can you open a pull request with that change?