run-tests.py: Make tests run with python2.3 if HGTEST_* is set.

optparse of python2.3 does not transform default values to the specified
type so e.g. "HGTEST_JOBS=4" (introduced in 07c3cd695b48) causes tests
to abort, because options.jobs is set to '4' instead of the number 4.

tests/run-tests.py

@@ -67,7 +67,7 b' parser.add_option("--with-hg", type="str'
     help="test existing install at given location")
 
 for option, default in defaults.items():
-    defaults[option] = os.environ.get(*default)
+    defaults[option] = int(os.environ.get(*default))
 parser.set_defaults(**defaults)
 (options, args) = parser.parse_args()
 verbose = options.verbose