Description of problem:
Due to operator error, I managed to create an empty jar file (containing only
META-INF/MANIFEST.MF).  Then aot-compile-rpm crashed:

+ /usr/bin/aot-compile-rpm
Traceback (most recent call last):
 File "/usr/bin/aot-compile-rpm", line 66, in <module>
   compiler.compile()
 File "/usr/lib/python2.5/site-packages/aotcompile.py", line 98, in compile
   self.writeMakefile(MAKEFILE, jobs)
 File "/usr/lib/python2.5/site-packages/aotcompile.py", line 124, in
writeMakefile
   (job.dsoName(), job.dbName()) for job in jobs]))}
TypeError: reduce() of empty sequence with no initial value
error: Bad exit status from /var/tmp/rpm-tmp.78936 (%install)

It took me a little digging through the code to figure out what that crash
meant.  It would be good to catch this exception and issue an error message
instead, perhaps "You dummy, there's nothing in your JAR file!"

Version-Release number of selected component (if applicable):
java-1.5.0-gcj-devel-1.5.0.0-14.fc7

How reproducible:
Always

Steps to Reproduce:
1. Write an RPM script that produces an empty jar file.  Have the %build script
execute "jar cf some.jar", for example.
2. Invoke aot-compile-rpm in the %install section
3. Invoke rpmbuild on the script
  
Actual results:
aot-compile-rpm crashes with the stacktrace given above

Expected results:
aot-compile-rpm should instead warn that it was given an empty JAR file

Additional info: