Fix the timestamp shown during cabal update

Passing an index-state timestamp to cabal update currently makes it
write a message saying the index has been updated to the *previous*
timestamp.

    $ cabal update hackage.haskell.org,2016-09-24T17:47:48Z
    Downloading the latest package list from hackage.haskell.org
    Package list of hackage.haskell.org is up to date at index-state 2022-01-27T12:59:23Z

This is because of a confusion between downloading the index and setting
the index state. These are independent actions.

This patch makes separates the two messages (updating the index and
updating the index-state timestamp) and makes sure the right timestamp
is printed.

cabal-install/src/Distribution/Client/CmdUpdate.hs

@@ -45,7 +45,6 @@ import Distribution.Simple.Utils
          ( die', notice, wrapText, writeFileAtomic, noticeNoWrap )
 import Distribution.Verbosity
          ( normal, lessVerbose )
-import Distribution.Client.IndexUtils.Timestamp
 import Distribution.Client.IndexUtils.IndexState
 import Distribution.Client.IndexUtils
          ( updateRepoIndexCache, Index(..), writeIndexTimestamp
@@ -201,7 +200,8 @@ updateRepo verbosity _updateFlags repoCtxt (repo, indexState) = do
               then Just `fmap` getCurrentTime
               else return Nothing
       updated <- Sec.uncheckClientErrors $ Sec.checkForUpdates repoSecure ce
-
+      -- this resolves indexState (which could be HEAD) into a timestamp
+      new_ts <- currentIndexTimestamp (lessVerbose verbosity) repoCtxt repo
       let rname = remoteRepoName (repoRemote repo)
 
       -- Update cabal's internal index as well so that it's not out of sync
@@ -211,20 +211,20 @@ updateRepo verbosity _updateFlags repoCtxt (repo, indexState) = do
           now <- getCurrentTime
           setModificationTime (indexBaseName repo <.> "tar") now
           noticeNoWrap verbosity $
-            "Package list of " ++ prettyShow rname ++
-            " is up to date at index-state " ++ prettyShow (IndexStateTime current_ts)
+            "Package list of " ++ prettyShow rname ++ " is up to date."
 
         Sec.HasUpdates -> do
           updateRepoIndexCache verbosity index
-          new_ts <- currentIndexTimestamp (lessVerbose verbosity) repoCtxt repo
           noticeNoWrap verbosity $
-            "Updated package list of " ++ prettyShow rname ++
-            " to the index-state " ++ prettyShow (IndexStateTime new_ts)
-
-          -- TODO: This will print multiple times if there are multiple
-          -- repositories: main problem is we don't have a way of updating
-          -- a specific repo.  Once we implement that, update this.
-          when (current_ts /= nullTimestamp) $
-            noticeNoWrap verbosity $
-              "To revert to previous state run:\n" ++
-              "    cabal v2-update '" ++ prettyShow (UpdateRequest rname (IndexStateTime current_ts)) ++ "'\n"
+            "Package list of " ++ prettyShow rname ++ " has been updated."
+
+      noticeNoWrap verbosity $
+        "The index-state is set to " ++ prettyShow (IndexStateTime new_ts) ++ "."
+
+      -- TODO: This will print multiple times if there are multiple
+      -- repositories: main problem is we don't have a way of updating
+      -- a specific repo.  Once we implement that, update this.
+      when (new_ts /= current_ts) $
+        noticeNoWrap verbosity $
+          "To revert to previous state run:\n" ++
+          "    cabal v2-update '" ++ prettyShow (UpdateRequest rname (IndexStateTime current_ts)) ++ "'\n"