Mediawiki Syntax in Image Captions Breaks Image Parsing

When the mediawiki parser encounters a mediawiki image with mediawiki sytax in it's caption, it fails to parse it properly, and consequently the output is mangled form of the original mediawiki syntax (when coverting to plaintext, for example). For example, the following image:

[[Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a [[Diggers]] document by [[William Everard (Digger)|William Everard]]]]

Is improperly parsed due to the links in the image's caption, and the result (if converted to plaintext) is:

Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a Diggers document by William Everard (Digger)|William Everard]]

I am fairly certain that this is due to the nested mediawiki syntax, because the following is parsed correctly:

[[Image:Levellers declaration and standard.gif]]