[IMP] safe_eval: let AuthenticationError and werkzeug HTTPExceptions bubble up

- Werkzeug's HTTPException are useful while dispatching HTTP requests,
  in order to return a custom error page with an appropriate status
  code. The http stack should let those exceptions bubble all the way up
  and return the body of the exception as the HTTP response.

- openerp.http.AuthenticationError may be useful while dispatching JSON
  requests, because the JSON error result will have error code 100
  instead of the usual code 200, making it easy to distinguish
  in simple JSON client code.

- Also slightly improved the fallback for unknown exceptions occurring
  during "safe evaluation", to explicitly mention the original exception
  type in the generic ValueError that gets raised.

openerp/tools/safe_eval.py

@@ -19,6 +19,7 @@ from opcode import HAVE_ARGUMENT, opmap, opname
 from psycopg2 import OperationalError
 from types import CodeType
 import logging
+import werkzeug
 
 from .misc import ustr
 
@@ -306,6 +307,10 @@ def safe_eval(expr, globals_dict=None, locals_dict=None, mode="eval", nocopy=Fal
         raise
     except openerp.exceptions.AccessError:
         raise
+    except werkzeug.exceptions.HTTPException:
+        raise
+    except openerp.http.AuthenticationError:
+        raise
     except OperationalError:
         # Do not hide PostgreSQL low-level exceptions, to let the auto-replay
         # of serialized transactions work its magic
@@ -315,4 +320,4 @@ def safe_eval(expr, globals_dict=None, locals_dict=None, mode="eval", nocopy=Fal
     except Exception, e:
         import sys
         exc_info = sys.exc_info()
-        raise ValueError, '"%s" while evaluating\n%r' % (ustr(e), expr), exc_info[2]
+        raise ValueError, '%s: "%s" while evaluating\n%r' % (ustr(type(e)), ustr(e), expr), exc_info[2]