The file gncal/calendar-week.c contains a non-ascii character that
causes many warnings from xgettext when I update the sv.po (which is in
UTF-8) with "intltool-update sv":

xgettext: warning: The following msgid contains non-ASCII characters.
                   This will cause problems to translators who use a
                   character encoding different from yours. Consider
                   using a pure ASCII msgid instead.
                   %s ‒ %s
xgettext: invalid multibyte sequence
xgettext: invalid multibyte sequence
xgettext: invalid multibyte sequence
xgettext: invalid multibyte sequence
xgettext: invalid multibyte sequence
xgettext: invalid multibyte sequence

Also, the character will not be displayed in the msgid in the po file,
it will simply be an extra space. Thus, this message cannot be translated
correctly as it is.