Package python-numpy is in no way required to build Zeitgeist, only to run it (there's a difference between Build Dependencies and Dependencies necessary to run it), and the ImportError message which is given is explicit enough for anyone who builds the package.
Listing the dependencies in a README or INSTALL file would be a nice thing to do, I'll write that down.
Thank you for your bug report.
Package python-numpy is in no way required to build Zeitgeist, only to run it (there's a difference between Build Dependencies and Dependencies necessary to run it), and the ImportError message which is given is explicit enough for anyone who builds the package.
Listing the dependencies in a README or INSTALL file would be a nice thing to do, I'll write that down.