Fix flake of large test run under Travis

[krzentner]

This should fix #2144 , but I don't know how to test it locally.

[codecov[bot]]

Codecov Report

Merging #2145 into master will increase coverage by 0.39%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2145      +/-   ##
==========================================
+ Coverage   91.47%   91.87%   +0.39%     
==========================================
  Files         195      195              
  Lines       10669    11023     +354     
  Branches     1337     1430      +93     
==========================================
+ Hits         9760    10127     +367     
+ Misses        661      635      -26     
- Partials      248      261      +13     

Impacted Files	Coverage Δ
...rage/tf/optimizers/conjugate_gradient_optimizer.py	81.90% <0.00%> (-1.81%)	:arrow_down:
src/garage/tf/algos/te_npo.py	93.03% <0.00%> (-1.22%)	:arrow_down:
src/garage/envs/wrappers/max_and_skip.py	100.00% <0.00%> (ø)
src/garage/envs/wrappers/stack_frames.py	100.00% <0.00%> (ø)
...garage/torch/policies/discrete_qf_argmax_policy.py	100.00% <0.00%> (ø)
src/garage/trainer.py	90.87% <0.00%> (+0.14%)	:arrow_up:
src/garage/tf/plotter/plotter.py	83.00% <0.00%> (+0.50%)	:arrow_up:
...arage/torch/q_functions/discrete_cnn_q_function.py	93.75% <0.00%> (+0.89%)	:arrow_up:
src/garage/sampler/multiprocessing_sampler.py	90.90% <0.00%> (+1.29%)	:arrow_up:
src/garage/np/_functions.py	86.06% <0.00%> (+1.63%)	:arrow_up:
... and 5 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update c0fd41d...8b8410b. Read the comment docs.

[krzentner]

@Mergifyio rebase

[mergify[bot]]

Command rebase: success

Branch has been successfully rebased