unit test for colgen loop when infeasible master (Farkas pricing)

[guimarqu]

Artur's suggestion to address the "No variable" warning in the LpSolver.

[12:17]guimarqu: hey, how do you start column generation when there is no variable in the master ? This happens at first colgen iteration using Farkas pricing
[14:55]Artur Pessoa: To use the solver, I had to add a dummy variable with upper and lower bound equal to zero and disable preprocessing.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e5e6c2b) 80.11% compared to head (7a3818c) 80.11%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1029   +/-   ##
=======================================
  Coverage   80.11%   80.11%           
=======================================
  Files          85       85           
  Lines        6428     6428           
=======================================
  Hits         5150     5150           
  Misses       1278     1278           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.