If you use alias modules in CVS the CVS support in hudson will not work. I
think this is an easy fix though--I'll suggest a couple of simple options below.

Under these conditions:

1. in CVSROOT/modules have an entry like

WebApp -a components/app components/web

(This is a module definition for 'WebApp' which is basically an alias for the
two modules components/app and components/web. You can use it anywhere you
would normally list those modules separately. It's a common mechanism for
assemblies.)

2. Update mode set to true or false--doesn't matter.

3. Legacy mode set to true (so that 'components' path element appears and is not
truncated just because it's got no repository files in it directly)

The code gets checked out okay but hudson falls over calculating changes because
it does a cvs log on "WebApp" but that's never going to work because there is no
directory called WebApp. So here's the error in the console:

$ computing changelog
cvs log: cannot open CVS/Entries for reading: No such file or directory
cvs [log aborted]: no repository

ERROR: cvs exited with error code 1
Command line was [Executing 'cvs' with arguments:
'-d:pserver:anonymous@oliver:/usr/local/repository/maintree'
'log'
'-d'
'>=2007-04-04'
'WebApp'

This is related to another problem: If I use an alias module then I have to use
legacy mode or I'll get a rather strange error because there's a mismatch
between the module I'm checking out and the directory I'm creating. The error
looks like this:

cvs checkout: existing repository /usr/local/repository/maintree/components/app
does not match /usr/local/repository/maintree/components/web
cvs checkout: ignoring module componets/web

It turns out both problems go away if I change the checkout of the code to use
the -N option, like this:

cvs co -Nd WebApp WebApp

This forces directory WebApp to get created with one subdirectory, components.

Now when you do the log on the 'WebApp' directory it will succeed.

Other options:

a) Since -N means don't shorten the path, maybe you don't want to change that
behavior. So instead you could change the 'legacy' mode so that it uses -Nd
instead of completely omitting -d. You get the full path checked out, but you
also get a new directory component 'WebApp'. It may not be ideal but I suspect
it's pretty much what you are trying to accomplish anyway...?

b) Keep checkout and legacy mode as they are, but change your log command. You
will get the same result whether or not you specify the cvs module in the log
command. I did an experiment. If you omit the module from the log command, it
runs on the code you have checked out anyway, and nothing more. So it's the
same result, but in the case where the module is WebApp and there is no WebApp
directory, it will still work (apparently).