be more clear about JAVA6/7_HOME and don't use silly defaults; on exc downloading file state which file failed

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1470150 13f79535-47bb-0310-9956-ffa450edef68

dev-tools/scripts/smokeTestRelease.py

@@ -71,11 +71,10 @@ def verifyJavaVersion(version):
 
 # http://s.apache.org/lusolr32rc2
 env = os.environ
-
 try:
   JAVA7_HOME = env['JAVA7_HOME']
 except KeyError:
-  JAVA7_HOME = '/usr/local/jdk1.7.0_01'
+  raise RuntimeError('please set JAVA7_HOME in the env before running smokeTestRelease')
 print('JAVA7_HOME is %s' % JAVA7_HOME)
 
 verifyJavaVersion('1.7')
@@ -131,6 +130,7 @@ def download(name, urlString, tmpDir, quiet=False):
     if not quiet and fileName.find('.asc') == -1:
       print('    already done: %.1f MB' % (os.path.getsize(fileName)/1024./1024.))
     return
+  try:
     fIn = urllib.request.urlopen(urlString)
     fOut = open(fileName, 'wb')
     success = False
@@ -150,6 +150,8 @@ def download(name, urlString, tmpDir, quiet=False):
         os.remove(fileName)
     if not quiet and fileName.find('.asc') == -1:
       print('    %.1f MB' % (os.path.getsize(fileName)/1024./1024.))
+  except Exception as e:
+    raise RuntimeError('failed to download url "%s"' % urlString) from e
   
 def load(urlString):
   return urllib.request.urlopen(urlString).read().decode('utf-8')
@@ -1276,6 +1278,8 @@ def main():
     print()
     print('Usage python -u %s BaseURL version tmpDir' % sys.argv[0])
     print()
+    print('  example: python3.2 -u dev-tools/scripts/smokeTestRelease.py http://people.apache.org/~whoever/staging_area/lucene-solr-4.3.0-RC1-rev1469340 4.3.0 /path/to/a/tmp/dir')
+    print()
     sys.exit(1)
 
   baseURL = sys.argv[1]