Apologies in advance for the laconic report -- I am exhausted at the moment.
I made a configuration change earlier that should have resulted in the Schema namespace getting enabled on test2wiki. It only half-worked: I was able to create an article in the Schema namespace, and it had the correct value for page_namespace in the database. But the namespace name was getting stripped from the title, transforming 'Schema:Test' into ':Test', as far as most interfaces were concerned. We ran scap after making the configuration change and later on I updating the i18n cache a second time, but that did not seem to fix things.
I do not think it's a static asset caching issue: interfaces generated by PHP that one would have expected to display the Schema were not displaying it.
I finally noticed a comment in CommonSettings.php, added by Gerrit change I147c16ecf1b235d4fec514d0c6f2ef10932caef9, that seemed relevant: Fundraising seems to have resorted to declaring the namespace manually, in the CommonSettings.php. I tried the same trick in I8ac1eae2456d845afe989052f188aea20f9f5d38 and it appears to have worked.
Relevant comments from mwalker on #wikimedia-tech (Fri Feb 15 01:29:37 UTC 2013):
17:25 <mwalker> right -- so that was because I was originally adding the namespaces via the $wgExtensionFunctions hook system
17:25 <mwalker> which happened too late
17:26 <mwalker> but, CanonicalNamespaces should always happen at the right time
17:26 <ori-l> Hrm.
17:27 <mwalker> I will say that I'm adding my namespace to both the $namespaces param in that hook; and then to all the other fun arrays
17:27 <mwalker> but -- I haven't tested this on test2
17:27 <mwalker> only test
I *do* use CanonicalNamespaces in EventLogging, so perhaps the problems aren't related after all. But for whatever reason adding the namespace manually in CommonSettings.php seems to have fixed my problem, too.