Confirmed. (Opera 12.16 on Linux here too.)
This only seems to happen inside code blocks (specifically, elements styled with
white-space: pre; inline code with
white-space: pre-wrap seems to be fine).
I don't see any real reason to have soft hyphens inside code blocks (except maybe in the mobile view, but the styling is different there anyway), so SE could just strip them out. In fact, adding a client-side fix to SOUP shouldn't be difficult, either.
That said, this really is a bug in Opera, and should be reported.*
The longer words in this text will be truncated in Opera.
These words will not be truncated in Opera.
*) In fact, I've just done that; the bug ID is DSK-388102.
Ps. While waiting for an official fix, I've added a client-side fix for this issue to the Stack Overflow Unofficial Patch v1.10 (which should also have significantly improved Opera compatibility in general). Basically, what my fix does is simply remove any soft hyphens found inside
<pre> tags on Opera.
I've also tried to make sure that the removal code gets re-run if any new posts are loaded by AJAX, or when the editor preview is updated. Alas, this latter feature seems to work somewhat unreliably, with the editor hooks sometimes failing to be applied. If anyone can figure out why that might be happening, please let me know! In the mean time, reloading the page seems to usually fix it.