CoreException: store at 'py_exn.artiq_core_exception'

... and fix a few imports

artiq/coredevice/comm_generic.py

@@ -457,8 +457,8 @@ class CommGeneric:
 
             self._write_header(_H2DMsgType.RPC_EXCEPTION)
 
-            if hasattr(exn, 'core_exception'):
-                exn = exn.core_exception
+            if hasattr(exn, 'artiq_core_exception'):
+                exn = exn.artiq_core_exception
                 self._write_string(exn.name)
                 self._write_string(exn.message)
                 for index in range(3):
@@ -504,15 +504,15 @@ class CommGeneric:
 
         traceback = list(reversed(symbolizer(backtrace))) + \
                     [(filename, line, column, function, None)]
-        core_exception = exceptions.CoreException(name, message, params, traceback)
+        core_exn = exceptions.CoreException(name, message, params, traceback)
 
-        if core_exception.id == 0:
-            python_exn_type = getattr(exceptions, core_exception.name.split('.')[-1])
+        if core_exn.id == 0:
+            python_exn_type = getattr(exceptions, core_exn.name.split('.')[-1])
         else:
-            python_exn_type = object_map.retrieve(core_exception.id)
+            python_exn_type = object_map.retrieve(core_exn.id)
 
         python_exn = python_exn_type(message.format(*params))
-        python_exn.core_exception = core_exception
+        python_exn.artiq_core_exception = core_exn
         raise python_exn
 
     def serve(self, object_map, symbolizer):

artiq/coredevice/exceptions.py

@@ -1,4 +1,8 @@
 import builtins
+import linecache
+import re
+import os
+
 from artiq.coredevice.runtime import source_loader
 
 

artiq/frontend/artiq_run.py

@@ -132,8 +132,8 @@ def run(with_file=False):
     except CompileError as error:
         return
     except Exception as exn:
-        if hasattr(exn, 'core_exception'):
-            print(exn.core_exception, file=sys.stderr)
+        if hasattr(exn, 'artiq_core_exception'):
+            print(exn.artiq_core_exception, file=sys.stderr)
         raise exn
     finally:
         device_mgr.close_devices()

artiq/language/core.py

@@ -2,7 +2,6 @@
 Core ARTIQ extensions to the Python language.
 """
 
-import os, linecache, re
 from collections import namedtuple
 from functools import wraps