Taken from http://issues.apache.org/bugzilla/show_bug.cgi?id=41090
http://issues.apache.org/bugzilla/attachment.cgi?id=19296

diff -Naur apache-ant-1.7.0/src/main/org/apache/tools/ant/taskdefs/optional/ssh/ScpToMessage.java apache-ant-1.7.0_20061221/src/main/org/apache/tools/ant/taskdefs/optional/ssh/ScpToMessage.java
--- apache-ant-1.7.0/src/main/org/apache/tools/ant/taskdefs/optional/ssh/ScpToMessage.java	2006-12-12 22:16:20.000000000 +0000
+++ apache-ant-1.7.0_20061221/src/main/org/apache/tools/ant/taskdefs/optional/ssh/ScpToMessage.java	2006-12-21 07:38:27.000000000 +0000
@@ -209,6 +209,7 @@
         waitForAck(in);
         sendDirectory(directory, in, out);
         out.write("E\n".getBytes());
+        out.flush();
         waitForAck(in);
     }