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
ry</a><a href='/guix/refs/?id=f5f642058a3b6bf3eda5eb714ad5fa1f0a2b1b20'>refs</a><a class='active' href='/guix/log/gnu/packages/idris.scm'>log</a><a href='/guix/tree/gnu/packages/idris.scm?id=f5f642058a3b6bf3eda5eb714ad5fa1f0a2b1b20'>tree</a><a href='/guix/commit/gnu/packages/idris.scm?id=f5f642058a3b6bf3eda5eb714ad5fa1f0a2b1b20'>commit</a><a href='/guix/diff/gnu/packages/idris.scm?id=f5f642058a3b6bf3eda5eb714ad5fa1f0a2b1b20'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/idris.scm'>
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<tr><td><span title='2020-08-29 11:29:43 -0400'>2020-08-29</span></td><td><a href='/guix/commit/gnu/packages/idris.scm?id=5aaa1995922285d53a97824f2b83bdb71ec9fdd0'>gnu: idris: Fix for Haskell build system changes.</a><span class='msg-avail'>...<span class='msg-tooltip'>See also 9e5496e0ae0ee8f638ca93949ecca314fdb9251e and
718dc7d4a5e5d26cac80c79d78535677e0379dc8.

* gnu/packages/idris.scm (idris)[arguments]: Add a phase that sets
'LD_LIBRARY_PATH', and one that restores the 'libidris_rts.a'
library back to the default output.
</span></span></td><td>Timothy Sample</td></tr>