~ /evolution-data-server-3.2.3/calendar/backends/caldav/e-cal-backend-caldav.c


/* ensure etag is quoted (to workaround potential server bugs) */
static gchar *
quote_etag (const gchar *etag)
{
        gchar *ret;

        if (etag && (strlen (etag) < 2 || etag[strlen (etag) - 1] != '\"')) {
                ret = g_strdup_printf ("\"%s\"", etag);
        } else {
                ret = g_strdup (etag);
        }

        return ret;
}


Returning:
davical: LOG: headers:-->If-Match: \\"5271cef89123fcca4bbe701e872b0a42\\"