variation_information(): fix docstring default

3 jobs for master in 97 minutes and 11 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #4997
amd64
job_clang_amd64

01:37:10

passed #4998
amd64
job_clang_cxx_amd64

00:55:52

passed #4996
amd64
job_gcc_amd64

00:55:05