typo fix following code review.

theano/configdefaults.py

@@ -346,7 +346,7 @@ AddConfigVar('warn.vm_gc_bug',
         " If your code was affected by this bug, a warning"
         " will be printed during the code execution if you use the"
         "`linker=vm,vm.lazy=True,warn.vm_gc_bug=True` Theano flags."
-        "This warning is diabled by default as it was not released.",
+        "This warning is disabled by default as the bug was not released.",
         BoolParam(False),
         in_c_key=False)
 

theano/gof/vm.py

@@ -404,7 +404,7 @@ class Stack(VM):
                                                 'destroy_map',
                                                 False)):
                                         warnings.warn(
-        "There was bug that existed in the default Theano configuration"
+        "There was a bug that existed in the default Theano configuration"
         " just in the development version between July 5 2012"
         " and July 30 2012. This was not in a released version."
         "The bug was affecting this script.",
@@ -523,7 +523,7 @@ class VM_Linker(link.LocalLinker):
         lazy - Useful only when use_cloop is False. When lazy is None, use the
             theano flag vm.lazy value. Then if we have a None(default) we auto
             detect if lazy evaluation is needed and use the apropriate
-            version. If lazy it is True or False, we force the version used
+            version. If lazy is True or False, we force the version used
             between Loop/LoopGC and Stack.
 
         """