Regression: text lines print twice

We observed a regression after my series of patches. In some configurations the text output would be doubled and result in output of the form:

[root@node ~]# ./executable
Message 1/4
Message 1/4
Message 2/4
Message 2/4
⠉ [3s] [=>                  ] 2/100 Progress message

I'm fully committed to fixing my mess and have identified the change responsible.

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