Preserve sys.executable after first stage.

econtext/core.py

@@ -1049,8 +1049,11 @@ class ExternalContext(object):
 
                 self.router.register(self.parent, self.stream)
                 self.router.register(self.master, self.stream)
+
+                sys.executable, = eval(os.environ.pop('ARGV0'))
                 LOG.debug('Connected to %s; my ID is %r, PID is %r',
                           self.parent, context_id, os.getpid())
+                LOG.debug('Recovered sys.executable: %r', sys.executable)
 
                 self._dispatch_calls()
                 LOG.debug('ExternalContext.main() normal exit')

econtext/master.py

@@ -361,6 +361,7 @@ class Stream(econtext.core.Stream):
             os.dup2(R,0)
             os.dup2(R2,101)
             for f in R,R2,W,W2: os.close(f)
+            os.environ['ARGV0'] = `[sys.executable]`
             os.execv(sys.executable,['econtext:CONTEXT_NAME'])
         else:
             os.write(1, 'EC0\n')