Be specific about nonexistent or non-directory directory.

PR: 24627
Based on Alexey Solofnenko's patch


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@277912 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/ExecTask.java

@@ -484,12 +484,10 @@ public class ExecTask extends Task {
             throw new BuildException("no executable specified", getLocation());
         }
         if (dir != null && !dir.exists()) {
-            throw new BuildException("The directory you specified does not "
-                                     + "exist");
+            throw new BuildException("The directory " + dir + " does not exist");
         }
         if (dir != null && !dir.isDirectory()) {
-            throw new BuildException("The directory you specified is not a "
-                                     + "directory");
+            throw new BuildException(dir + " is not a directory");
         }
         if (spawn && incompatibleWithSpawn) {
             getProject().log("spawn does not allow attributes related to input, "