Random bug in test_da.py

[Hv0nnus]

Describe the bug

The function test_da.py sometime bug. This bug has not been detected as it occurs randomly (no seed is fixed in this test).

To Reproduce

Steps to reproduce the behavior:

Expected behavior

At least the test should have fixed seed, but it is strange that this error occur, thus it might be a problem in the functions used.

Environment (please complete the following information):

• OS (e.g. MacOS, Windows, Linux): Linux
• Python version: 3.7
• How was POT installed (source, pip, conda): conda
• Build command you used (if compiling from source):
• Only for GPU related bugs:
  • CUDA version:
  • GPU models and configuration:
  • Any other relevant information:

Output of the following code snippet:
Linux-5.4.0-77-generic-x86_64-with-debian-buster-sid
Python 3.7.6 (default, Jan 8 2020, 19:59:22)
[GCC 7.3.0]
NumPy 1.17.4
SciPy 1.3.2
POT 0.6.0 (this was tested also on the 0.7.0 version)

Additional context