Clean theme news article truncation mishandling line-breaks

[StephDriver]

Describe the bug
Clean theme, Janeway 1.5.1. News Articles are truncated into a summary for use e.g. on homepage. When article text has a new line, this is ignored rather than replaced with a space, such that the strings run together. Does not always happen to every linebreak.

for example:

term!The runs together but expression. The does not

But then in

both Conference!This and editors.Our run together

[joemull]

I'm not positive but I think your changes in #3831 would have fixed this.

[StephDriver]

I'm not positive but I think your changes in #3831 would have fixed this.

that might explain my déjà vu when investigating this.

But I'm not sure it does fix it. I think the issue here is that it's fine when there is a trailing whitespace at the end of the previous line, but not when not - which suggests to me that lines are being concatenated without any whitespace added. I don't recall specifically testing for that behaviour when making the #3831 fix.

Assigning this to myself to investigate (I'll test the update for this specific behaviour).