Fixed a possible "Cannot create a file when that file already exists"...

    Fixed a possible "Cannot create a file when that file already exists" error in managed Windows slave launcher.
    <a href="http://www.nabble.com/%22Cannot-create-a-file-when-that-file-already-exists%22---huh--td23949362.html#a23950643">report</a>

SmbFile.mkdirs() behave differently to File.mkdirs(), and it fails if the directory already exists.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@19321 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/os/windows/ManagedWindowsServiceLauncher.java

@@ -117,8 +117,9 @@ public class ManagedWindowsServiceLauncher extends ComputerLauncher {
                     logger.println(Messages.ManagedWindowsServiceLauncher_DotNetRequired());
                     return;
                 }
-    
-                remoteRoot.mkdirs();
+
+                if(!remoteRoot.exists())
+                    remoteRoot.mkdirs();
 
                 // copy exe
                 logger.println(Messages.ManagedWindowsServiceLauncher_CopyingSlaveExe());