Nant Task cannot handle parameters with multiple values which contain space

This issue is something similar to the bug affecting MSBUILD at BAM-13608

The options is something like:

/D:arg="/xml:Result.xml /exclude:Nightly" /D:TestsPath="src\Tests"

The build fails with the message

Unknown argument '/exclude:Nightly'

the space has made bamboo to view it as a separate argument.

Workaround
Replace the quotes with single quotes. Something like below will work

/D:arg='/xml:Result.xml /exclude:Nightly' /D:TestsPath='src\Tests'