In VisualEditor, enter

one[space][Ctrl-I]two[space][Ctrl-I]three

This will result in wiki text

one ''two ''three

but clearly

one ''two'' three

was intended. I don't think a trailing (or leading?) space in italic/bold wikitext is ever appropriate.

The fixed Bug 33108 is similar but deals with selected text.

<editorial>
I believe some of the hostility towards VE in the Wikipedia community results from issues like this: editors with long watchlists feel they have to clean up after many such VE edits.
</editorial>

Version: unspecified
Severity: normal