It would be useful if the groovy postbuild plugin had a method to check if a file with a given pattern existed in the jenkins workspace. This could be used to easily determine the state of a build by looking for marker files.

Possible interface (If Jenkins has some concept of a FileTree / FileCollection that could be used):

// searches the entire workspace for file names that match regexp
fileExists(String regexp)
 
// searches for files in dir recursively for file names that match regexp
fileExists(File dir, String regexp)

Example:

if (manager.fileExists(new File("build/customverification/"), ".*\\.failed")) {
    manager.addBadge(...)
    manager.buildUnstable();
    ...
}