Temp directory deleted and not recreated after stop/start

When Jetty is started with JSP 2.1, and then a context is stopped and started using JMX, the temp directory for the context is deleted but not created.

After restart, the following message is logged:

WARN EmbeddedServletOptions PWC5963: The scratchDir you specified: <temp_dir_name>\jsp is unusable.

If Jetty is started without JSP, the problem does not appear.

Suggested fix:

In org.mortbay.jetty.webapp.WebAppContext getTempDirectory(), change the initial test from

if (_tmpDir!=null)
return _tmpDir;

to:

if (_tmpDir!=null && _tmpDir.isDirectory() && _tmpDir.canWrite())
return _tmpDir;