Concretely, the plugin “Use Google Libraries” uses URLs like  src=’//ajax.googleapis.com/ajax/libs/…’. Those were rewritten by mistake into src=’/ajax/libs/…’

I couldn’t disable the plugin “Root Relative URLs” as it’s the only way to make my blog accessible seamlessly from both internet and my intranet, using either the netbios name of my NAS, its IP or its dynamic DNS name.

So, I tried to add //ajax.googleapis.com in the “black list urls” of  “Root Relative URLs”. Those can be set in the Dashboard > Settings > General > (scroll to the bottom) “Root Relative Blacklist URLs”.

Unfortunately it didn’t work… Until Hube2, who wrote a hack of “Root Relative URLs”, told me how to set it correctly: one may not use the domain name in the black listed URL’s.

Conclusion, in my case, I had to black list “ajax/libs”, et voilà!