BAM-7027 Tony Much comment:

Here is some more feedback, this time based on experience running 2.7 beta2 on Windows XP:

Tried simple Maven 2 Builder with Goal : "-B release:prepare".
The problem remains the same. Result shows nested ""-s and commit fails with errorcode 1. See previous posts for log example.
I added also : "Verbose logs: true " for Mercurial repository configuration. I see in configuration that : "This Job will use all Repository settings from the plan".
Unfortunately, I cannot see any extra verbosity nor debug info. Can I somehow turn on additional debugging? How?
I also tried separately, giving several release specific parameters (version etc.) as arguments, result is the same.

If my config seems enough/OK then I think this is a real blocker issue.

By the way, if Maven plugin ("release:prepare" for example) expects some command line input from user then Bamboo Agent keeps on waiting for that input and cannot be killed / shut down / disabled without Bamboo server restart. This can be tested if you add Maven builder goal "release:prepare" and run it.

good luck