optimize getting the epoch

--HG--
branch : 3.0
7 jobs for topic/3.0/nojdcal in 4 minutes and 25 seconds (queued for 1 second)
Name Stage Failure
failed
test-python37 Test
  nopillow: commands succeeded
xfail: commands succeeded
pandas: commands succeeded
numpy: commands succeeded
ERROR: doc: parallel child exit code 1
ERROR: doctest: parallel child exit code 1
Running after_script
Uploading artifacts for failed job
ERROR: Job failed: exit code 1