Kilian Weishaupt authored May 26, 2020 and Timo Koch committed May 26, 2020

[test] Use python3 for test wrappers

See merge request !2138

(cherry picked from commit 141fe13d)

20fb36ba [test] Use python3 for test wrappers

[test][convergence] Change condition of checking error i twice to checking error i and error i+1 once.

When running the tests in parallel the box- and tpfa-specific tests were
using and overwriting the same grid file, which lead to invalid grids
during the convergence tests.