When changing dirs resolve to the coorect separator conventions

PR:	10755


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@274211 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/optional/net/FTP.java

@@ -667,7 +667,7 @@ public class FTP
             String cwd = ftp.printWorkingDirectory();
             String parent = dir.getParent();
             if (parent != null) {
-                if (!ftp.changeWorkingDirectory(parent)) {
+                if (!ftp.changeWorkingDirectory(resolveFile(parent))) {
                     throw new BuildException("could not change to " 
                         + "directory: " + ftp.getReplyString());
                 }