Unable to set the working directory for projects where the master pom isn't at the root of the project

Branches and Tags are created from the current working directory, which isn't always correct and there isn't a way to override the working directory.

For example, we have the following directory structure:

${root}/master/pom.xml - The modules section include relative paths to modules a, b, and c.
${root}/module-a/pom.xml
${root}/module-b/pom.xml
${root}/module-c/pom.xml

All subversion copies (via branch or prepare) originate from ${root}/master. As a result, they are incomplete; we really want to create copies from ${root} not ${root}/master. Here's the subversion command that I think is the problem:

[INFO] Working directory: C:\devsys\repos\trunk\master
[INFO] Branching release with the label release-1.0...
[INFO] Executing: svn --non-interactive copy --file C:\Users\cnelson\AppData\Local\Temp\maven-scm-1179760787.commit . http://hostname/svn/dev/branches/release-1.0

The period after the filename is what's indicating to subversion to create the copy from master instead of ${root}. Note: the working directory is derived from the basedir and I couldn't find a way to override the basedir.

While not having the master pom at the root of the project may be a little uncommon, it doesn't seem unreasonable. Can we add a configuration option to handle these cases?