Change message to present tense

src/librustc/lint/builtin.rs

@@ -584,7 +584,7 @@ impl BuiltinLintDiagnostics {
                     let introduced = if is_imported { "imported" } else { "defined" };
                     db.span_label(
                         span,
-                        format!("the item `{}` was already {} here", ident, introduced)
+                        format!("the item `{}` is already {} here", ident, introduced)
                     );
                 }
             }

src/test/ui/lint/lint-unused-imports.stderr

@@ -45,7 +45,7 @@ LL | |     fn f() {
 LL | |         self::g();
 LL | |     }
 LL | | }
-   | |_- the item `g` was already defined here
+   | |_- the item `g` is already defined here
 
 error: unused import: `self::g`
   --> $DIR/lint-unused-imports.rs:68:9
@@ -57,7 +57,7 @@ error: the item `foo` is imported redundantly
   --> $DIR/lint-unused-imports.rs:78:9
    |
 LL | use test2::{foo, bar};
-   |             --- the item `foo` was already imported here
+   |             --- the item `foo` is already imported here
 ...
 LL |     use test2::foo;
    |         ^^^^^^^^^^

src/test/ui/lint/use-redundant.stderr

@@ -20,7 +20,7 @@ warning: the item `Bar` is imported redundantly
   --> $DIR/use-redundant.rs:21:9
    |
 LL | use crate::foo::Bar;
-   |     --------------- the item `Bar` was already imported here
+   |     --------------- the item `Bar` is already imported here
 ...
 LL |     use crate::foo::Bar;
    |         ^^^^^^^^^^^^^^^
@@ -29,7 +29,7 @@ warning: the item `S` is imported redundantly
   --> $DIR/use-redundant.rs:25:9
    |
 LL | use m1::*;
-   |     ----- the item `S` was already imported here
+   |     ----- the item `S` is already imported here
 ...
 LL |     use m1::S;
    |         ^^^^^