add Always use virtualenv flag

[artem-fedorov]

No description provided.

[codecov-io]

Codecov Report

Merging #116 into master will increase coverage by 0.09%.
The diff coverage is 80%.

@@            Coverage Diff             @@
##           master     #116      +/-   ##
==========================================
+ Coverage   64.55%   64.64%   +0.09%     
==========================================
  Files          44       44              
  Lines        3608     3612       +4     
  Branches      615      615              
==========================================
+ Hits         2329     2335       +6     
  Misses       1108     1108              
+ Partials      171      169       -2

Impacted Files	Coverage Δ
...lugins/performance/build/PerformanceTestBuild.java	61.97% <80%> (+1.1%)	⬆️
...dson/plugins/performance/PerformanceReportMap.java	66.46% <0%> (+0.6%)	⬆️
...ns/performance/actions/PerformanceBuildAction.java	81.25% <0%> (+3.12%)	⬆️

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