Test for joining lines with 'joinspaces' set or not

STARTTEST
:set nojoinspaces
/firstline/
jJjJjJjJjJjJjJjJjJjJjJjJjJjJ:set joinspaces
jJjJjJjJjJjJjJjJjJjJjJjJjJjJ:?firstline?+1,$w! test.out
:qa!
ENDTEST

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