tests/test-gendoc-sv.t

extdata: abort if external command exits with non-zero status (BC)

Per the last discussion, this is more reliable and consistent way than
suppressing an error. For grep, erroring out might be inconvenient, but
for curl, non-zero exit status should be detected. The latter wouldn't be
possible if non-zero status is ignored.

https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-October/105727.html

#require docutils gettext

  $ $TESTDIR/check-gendoc sv
  checking for parse errors