This matches the change made to text formatting and quoting styles in emacs
25.1.
From (elisp) Displaying Messages:
The ‘text-quoting-style’ variable controls what quotes are
generated; *Note Keys in Documentation::. A call using a format
like "Missing `%s'" with grave accents and apostrophes typically
generates a message like "Missing ‘foo’" with matching curved
quotes. In contrast, a call using a format like "Missing '%s'"
with only apostrophes typically generates a message like "Missing
’foo’" with only closing curved quotes, an unusual style in
English.
This matches the change made to text formatting and quoting styles in emacs 25.1.
From (elisp) Displaying Messages:
Now,
prints as: