https://en.wikipedia.org/w/index.php?title=Mazda_Demio&diff=638149187&oldid=637019310 (December 2014)
and some more recent examples in 2015:
https://en.wikipedia.org/w/index.php?title=Guy_Bedarida&diff=653362464&oldid=653362034 (March 24)
https://en.wikipedia.org/w/index.php?title=Walking_on_a_Dream&diff=653533175&oldid=651714967 (March 25)
and perhaps more.
<span class="">
<span lang="en-US">
have also been reported
Thanks for the report. These are both pretty old diffs, though; is this still occurring? At least <span lang="en-US"> was definitely fixed by one of Ed's patches about a month ago, others might be long fixed too.
I've also been unable to reproduce this on Firefox and Chrome, both using the standard and the mobile site. Mostly I tried making edits that didn't have any effect or much of an effect. Since I can't reproduce it and the bug was apparently fixed recently, I'm closing this issue - hope I don't step on any toes in doing so.
https://en.wikipedia.org/w/index.php?title=Nanolithography&diff=661875076&oldid=661874958 (May 11)
"25 nm" was replaced by "25<span> </span>nm."
I reopened it since I found an example on May 11. Feel free to close again if the issue was fixed after that date.
Significantly after that date; should have been fixed around 22 May (but caching applies).