Per user complaint on MediaWiki-General. It appears that "namespace" is a reserved word on some versions of PHP 5 (even though it should not yet be). In any case, it will officially be at some point, so the use of the class named "Namespace" needs to be changed, as this causes "unexpected T_NAMESPACE" errors when Namespace.php is loaded on those versions of PHP. Rather than attach a large patch to do this, which may get out of date, here's some code to make the needed change from "Namespace" to MWNamespace":
mv includes/Namespace.php includes/MWNamespace.php
find . \( -name "*.php" -o -name "*.inc" \) -exec grep -l Namespace {} \; | \
xargs perl -pi -e 's/\bNamespace(\.php|::)/MWNamespace$1/'
Obviously, I'm not going to commit such a large change without discussion, hence this bug.
Version: 1.12.x
Severity: major