Created attachment 101005 [details]
A set of test cases

In some situations, a no-break space (U+00A0) or non-breaking hyphen (U+2011) prevents a valid line break after a normal hyphen (U+002D, U+2010) or dash (U+2013, U+2014) or soft hyphen (U+00AD) that occurs within the preceding word. Specifically, this only seems to happen if the preceding word is also the first word in the paragraph (which means that the issue is unlikely to emerge unless the paragraph begins with a long word or string and the line is rather short).

Reproducible: always
Found in LO 3.5.4.2 (on Debian stable), 4.2.4.2 (on Windows), and 4.3.0.0.beta2 (on both Debian and Windows)

As a workaround, you could use a narrow no-break space (U+202F), a combination of word joiner (U+2060) and normal space (U+0020), or a combination of a regular hyphen (U+002D) and word joiner.

Note: this issue looks similar to bug 58477 but only occurs in a very specific situation. I also occurs on Windows, and in LO 3.5.4.2 and 4.3.0.0.beta2, which are not affected by 58477.