Reword index-state mismatch warning

Author: jasagredo

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

@@ -277,15 +277,15 @@ getSourcePackagesAtIndexState verbosity repoCtxt mb_idxState mb_activeRepos = do
             when (isiMaxTime isi /= ts0) $
                 if ts0 > isiMaxTime isi
                     then warn verbosity $
-                                   "Requested index-state " ++ prettyShow ts0
-                                ++ " is newer than '" ++ unRepoName rname ++ "'!"
-                                ++ " Falling back to older state ("
-                                ++ prettyShow (isiMaxTime isi) ++ ")."
+                                   "There is no index-state for '"
+                                ++ unRepoName rname ++ "' exactly at the requested timestamp ("
+                                ++ prettyShow ts0 ++ "). Falling back to the previous index-state that exists: "
+                                ++ prettyShow (isiMaxTime isi) ++ ". Suggestion: use this other timestamp instead of the one you provided, the build plan will be the same."
                     else info verbosity $
-                                   "Requested index-state " ++ prettyShow ts0
-                                ++ " does not exist in '"++ unRepoName rname ++"'!"
-                                ++ " Falling back to older state ("
-                                ++ prettyShow (isiMaxTime isi) ++ ")."
+                                   "There is no index-state for '"
+                                ++ unRepoName rname ++ "' exactly at the requested timestamp ("
+                                ++ prettyShow ts0 ++ "). Falling back to the previous index-state that exists: "
+                                ++ prettyShow (isiMaxTime isi) ++ ". Suggestion: use this other timestamp instead of the one you provided, the build plan will be the same."
             info verbosity ("index-state("++ unRepoName rname ++") = " ++
                               prettyShow (isiMaxTime isi) ++ " (HEAD = " ++
                               prettyShow (isiHeadTime isi) ++ ")")