build_operation(op) (`actual`) not equal to "cdo  ymonmax [ 'file.nc' ] out.nc" (`expected`).

actual vs expected
- "cdo  ymonmax [ \"d:\\RCompile\\CRANincoming\\R-devel\\rcdo.Rcheck\\tests\\testthat\\file.nc\" ] out.nc"
+ "cdo  ymonmax [ 'file.nc' ] out.nc"