Merge branch 'paranoid_line_search' into 'NIFTy_6'

Try to avoid crashes in the line searcher

See merge request !550
14 jobs for NIFTy_6 in 26 minutes and 16 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build Docker
passed #1182192
build_docker_from_scratch

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  Test
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test_mpi

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test_serial

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86.0%
 
  Release
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pages

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  Demo Runs
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run_bernoulli

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run_curve_fitting

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run_getting_started_1

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run_getting_started_2

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run_getting_started_3

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run_getting_started_mf

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run_ipynb0

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passed #1182220
run_ipynb1

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passed #1182252
run_visual_mgvi

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  Deploy
passed pages:deploy

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