workaround for issue 1255 in PyPy

see https://bugs.pypy.org/issue1255 for details

unix/__init__.py

@@ -15,6 +15,24 @@ def hang_until_sig(extra_signals=[]):
     then also on those signals this call will release."""
     global end
 
+    # Ascertain what Python are we working on. 2012 PyPy and earlier
+    # may be affected by https://bugs.pypy.org/issue1255
+
+    bugged_pypy = False
+    try:
+        import platform
+    except:
+        pass
+    else:
+        if platform.python_implementation() == 'PyPy':
+            try:
+                mon, day, year = platform.python_build()[1].split(' ')
+                year = int(year)
+            except:
+                pass
+            else:
+                bugged_pypy = year <= 2012
+
     signal.signal(signal.SIGTERM, __sighandler)
     signal.signal(signal.SIGINT, __sighandler)
     for s in extra_signals:
@@ -22,7 +40,10 @@ def hang_until_sig(extra_signals=[]):
     
     while not end:
         try:
-            signal.pause()
+            if bugged_pypy:
+                time.sleep(1)   # see https://bugs.pypy.org/issue1255
+            else:            
+                signal.pause()
         except:         # pause() is undefined on Windows
             try:        # we will sleep for small periods of time
                 time.sleep(0.5)