Various bits of refactoring & cleanup

src/metabase/driver/generic_sql/query_processor.clj

@@ -131,7 +131,7 @@
      (formatted this false))
     ([{:keys [value base-type]} _]
      (cond
-       (instance? Timestamp value) (cast-as-date (u/date->yyyy-mm-dd value))
+       (instance? Timestamp value) (cast-as-date `(Timestamp/valueOf ~(.toString value))) ; prevent Clojure from converting this to #inst literal, which is a util.date
        (= base-type :UUIDField)    (java.util.UUID/fromString value)
        :else                       value))))
 

test/metabase/driver/query_processor_test.clj

@@ -757,10 +757,7 @@
 
 ;; There were 9 "sad toucan incidents" on 2015-06-02
 (datasets/expect-with-datasets #{:h2 :postgres :mysql}
-  (datasets/dataset-case
-    :h2       9
-    :postgres 9
-    :mysql    10) ; not sure exactly these disagree
+  9
   (Q dataset sad-toucan-incidents
      of incidents
      filter and > timestamp "2015-06-01"