Applies to Web browsers (Firefox, Opera) that natively display SVG and require correct MIME type to be served from Moodle.
Internet Explorer + Adobe SVG Plugin view does not have a problem as it renders SVG base on the .svg extension alone.

Problem can be simply resolved by adding the following lines to function get_mimetypes_array() in /lib/filelib.php

i.e.

'svg' => array ('type'=>'image/svg+xml', 'icon'=>'image.gif'),
'svgz' => array ('type'=>'image/svg+xml', 'icon'=>'image.gif'),