Comment 1 for bug 1238197

at least this
tssetup = App(r'"c:\BUILD\Setup.exe"')

should be:
tssetup = App(r"c:\BUILD\Setup.exe")

because in your version the " will be part of the app file name and hence does not exist.
Additional quoting is not necessary with the App feature.

The App open feature will be revised in version 1.1.0

For now you might try the following:
app = os.path.join(r"\\tsarchive", "Storage", "Timeslips", "Installations", Settings.tsVersion, Settings.tsBuild, "setup.exe")
import java.lang.Runtime as RT
cmd = ("start", "/i", "/b", app)
RT.getRuntime().exec(cmd)

this will be used in version 1.1.0 for all situations, where we need to start something in parallel to Sikuli.