Add some in-body comments about 'except Exception:' business.

theano/gof/link.py

@@ -314,6 +314,7 @@ def streamline(env, thunks, order, post_thunk_old_storage = None, no_recycling =
                     thunk()
                     for old_s in old_storage:
                         old_s[0] = None
+            # N.B.: used instead of except: to not catch KeyboardInterrupt
             except Exception:
                 raise_with_op(node)
         f = streamline_default_f
@@ -325,6 +326,7 @@ def streamline(env, thunks, order, post_thunk_old_storage = None, no_recycling =
             try:
                 for thunk, node in thunk_node_list:
                     thunk()
+            # N.B.: used instead of except: to not catch KeyboardInterrupt
             except Exception:
                 raise_with_op(node)
         f = streamline_nice_errors_f
@@ -585,6 +587,7 @@ class WrapLinker(Linker):
             for i, (thunks, node) in enumerate(zip(thunk_groups, order)):
                 try:
                     wrapper(i, node, *thunks)
+                # N.B.: used instead of except: to not catch KeyboardInterrupt
                 except Exception:
                     raise_with_op(node)
         f.thunk_groups = thunk_groups