test-archive: gracefully handle HTTPErrors on get-with-headers

This avoids pritting out a traceback when a get-with-headers call causes hgweb
to respond with an HTTPError code.

tests/test-archive.t

@@ -69,10 +69,18 invalid arch type should give 404
   >     msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
   > except ImportError:
   >     pass
+  > if len(sys.argv) <= 3:
   > node, archive = sys.argv[1:]
-  > f = urllib2.urlopen('http://127.0.0.1:%s/?cmd=archive;node=%s;type=%s'
-  >                     % (os.environ['HGPORT'], node, archive))
+  >     requeststr = 'cmd=archive;node=%s;type=%s' % (node, archive)
+  > else:
+  >     node, archive, file = sys.argv[1:]
+  >     requeststr = 'cmd=archive;node=%s;type=%s;file=%s' % (node, archive, file)
+  > try:
+  >     f = urllib2.urlopen('http://127.0.0.1:%s/?%s'
+  >                     % (os.environ['HGPORT'], requeststr))
   > sys.stdout.write(f.read())
+  > except urllib2.HTTPError, e:
+  >     sys.stderr.write(str(e) + '\n')
   > EOF
   $ python getarchive.py "$TIP" gz | gunzip | tar tf - 2>/dev/null
   test-archive-2c0277f05ed4/.hg_archival.txt