Update safe_netrc from https://git.ligo.org/emfollow/safe-netrc

This brings support for the NETRC environment variable, which
makes it easier to isolate the unit tests from the users's
own netrc file.
10 jobs for update-safe-netrc in 5 minutes (queued for 10 seconds)
Status Job ID Name Coverage
  Build
passed #559084
build:debian:jessie

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build:debian:stretch

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build:el7

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build:tarball

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  Test
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docs

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syntax

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test:python2.7

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test:python3.5

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test:python3.6

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passed #559089
test:python3.7

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