Make PeachPy processes deterministic:

  https://github.com/Maratyszcza/PeachPy/issues/88
  https://issues.guix.gnu.org/50672

diff --git a/peachpy/name.py b/peachpy/name.py
index b6a03dc..412079d 100644
--- a/peachpy/name.py
+++ b/peachpy/name.py
@@ -86,13 +86,13 @@ def add_scoped_name(self, scoped_name):
                 self.names[scope_name.name] = scope
         else:
             assert scope_name.name is None
-            self.prenames.setdefault(scope_name.prename, set())
+            self.prenames.setdefault(scope_name.prename, {})
             if subscoped_name:
                 for subscope in iter(self.prenames[scope_name.prename]):
                     if isinstance(subscope, Namespace) and subscope.scope_name is scope_name:
                         subscope.add_scoped_name(subscoped_name)
                         return
-            self.prenames[scope_name.prename].add(scope)
+            self.prenames[scope_name.prename][scope] = None
 
     def assign_names(self):
         # Step 1: assign names to symbols with prenames with no conflicts
ummary</a><a href='/guix/refs/?id=0bf3466372afd981c55396e14a11c3eccaf1924e'>refs</a><a class='active' href='/guix/log/gnu/packages/wordnet.scm'>log</a><a href='/guix/tree/gnu/packages/wordnet.scm?id=0bf3466372afd981c55396e14a11c3eccaf1924e'>tree</a><a href='/guix/commit/gnu/packages/wordnet.scm?id=0bf3466372afd981c55396e14a11c3eccaf1924e'>commit</a><a href='/guix/diff/gnu/packages/wordnet.scm?id=0bf3466372afd981c55396e14a11c3eccaf1924e'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/wordnet.scm'>
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<tr><td><span title='2018-01-31 00:04:00 +0100'>2018-01-31</span></td><td><a href='/guix/commit/gnu/packages/wordnet.scm?id=fc12c5237c459ca13ac920b518aea4db8faa4555'>gnu: wordnet: Include PIC objects in libWN.a.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes a Dico build failure introduced in commit
a6a9e628693ed2d49cd9cdfca597fd4e63bbdef0.

* gnu/packages/wordnet.scm (wordnet)[arguments]: Add 'build-libwn-PIC'
phase.
</span></span></td><td>Ludovic Courtès</td></tr>