ZOOKEEPER-3094: Make BufferSizeTest reliable

ZKPatch: d8b825d6533e9848565beff09e9a018136ca32bd (extract)

Changes made to the testStartupFailure test to remember the old directory and switch back to it after the test has completed.

Author: Jeelani Mohamed Abdul Khader <mjeelani@devvm3360.prn2.facebook.com>

Reviewers: Michael Han <hanm@apache.org>, Norbert Kalmar

Closes #577 from mjeelanimsft/make-buffersizetest-reliable

src/java/test/org/apache/zookeeper/test/BufferSizeTest.java

@@ -121,12 +121,15 @@ public class BufferSizeTest extends ClientBase {
     private void testStartupFailure(File testDir, String failureMsg) throws Exception {
         stopServer();
         // Point server at testDir
+        File oldTmpDir = tmpDir;
         tmpDir = testDir;
         try {
             startServer();
             fail(failureMsg);
         } catch (IOException e) {
             LOG.info("Successfully caught IOException: " + e);
+        } finally {
+            tmpDir = oldTmpDir;
         }
     }
 }