update to test #1873, #1360

testsuite/tests/ghc-regress/ghci/prog009/A3.hs

+module A where where
+

testsuite/tests/ghc-regress/ghci/prog009/ghci.prog009.script

 :! cp A1.hs A.hs
+import Data.List
 :load A
-:show modules
+-- Data.List should still be in scope:
+:t nub
 :module +B
 yan
-:! touch A.hs
+:! sleep 1
+:! cp A3.hs A.hs
+:reload
+-- error, context drops to Prelude,Data.List
+-- Data.List should still be in scope:
+:t nub
+:! sleep 1
+:! cp A1.hs A.hs
 :reload
+-- ok again, B should be back in the context
 yan
--- should keep B in the context
+-- Data.List should still be in scope:
+:t nub
 :! sleep 1
 :! cp A2.hs A.hs
 :reload
 :show modules
-yan
-
+yan -- error

testsuite/tests/ghc-regress/ghci/prog009/ghci.prog009.stderr

 
+A.hs:1:15: parse error on input `where'
+
 <interactive>:1:0: Not in scope: `yan'

testsuite/tests/ghc-regress/ghci/prog009/ghci.prog009.stdout

-B                ( B.hs, interpreted )
-A                ( A.hs, interpreted )
+nub :: (Eq a) => [a] -> [a]
 "tan"
+nub :: (Eq a) => [a] -> [a]
 "tan"
+nub :: (Eq a) => [a] -> [a]
 A                ( A.hs, interpreted )