Please support automatic updating of a perforce mapping

As mentioned in another thread, we use fairly complex perforce mappings.
There's one path mapping for every component and third party library we
use. The client view templates typically contain 50-100 paths.

Because we need to change client view templates from time to time, we've
developed an internal tool that automatically checks and updates the
client view template as part of the nightly build process.

First, the "client view template" template is checked out, then the
local client is redefined with that template template and then all files
based on that template are checked out.

With TeamCity, this automatism doesn't work, because the TeamCity server
does the check out, transfers the code to the build agent and the build
agent runs the Ant script on that code. Now, our Ant script tries to
redefine the Perforce client view template which cannot work.

Is it possible to run an Ant script and/or Java application before the
Server checkout process in preparation of the next build? That would be
really helpful because currently, I've to manually keep the client view
template mapping in sync.

Thanks,

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Stefan Matthias Aust