serve.py: add duration/gps checks for backwards compatibility

9 jobs for master in 1 minute and 58 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Dist
passed #420768
dist:tarball

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  Build
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build:debian:stretch

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build:el7

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passed #420771
docs

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  Test
passed #420773
test:debian-python2:stretch

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passed #420774
test:debian-python3:stretch

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22.0%
passed #420772
test:el7-python2

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  Deploy
passed #420775
pages

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passed pages:deploy

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