Add better tests for web.py; fix some bugs found with spidering.

- _spider in web.py was actually failing to spider deeper than a certain
  point.
- Fixed multiprocessing pools to not use daemons and to allow recursive
  spawning.
- Added detailed tests for spidering and for finding archive versions.
- left some xfail URL finding exercises for the reader.
- Fix noqa annotations for some @when decorators

var/spack/repos/builtin/packages/elfutils/package.py

@@ -37,10 +37,10 @@ class Elfutils(AutotoolsPackage):
 
     url      = "https://sourceware.org/elfutils/ftp/0.168/elfutils-0.168.tar.bz2"
     list_url = "https://sourceware.org/elfutils/ftp"
-    list_depth = 2
+    list_depth = 1
 
-    version('0.168','52adfa40758d0d39e5d5c57689bf38d6')
-    version('0.163','77ce87f259987d2e54e4d87b86cbee41', preferred=True)
+    version('0.168', '52adfa40758d0d39e5d5c57689bf38d6')
+    version('0.163', '77ce87f259987d2e54e4d87b86cbee41', preferred=True)
 
     provides('elf@1')