guix lint: Remove "guix lint: " prefix from warnings.

This allows editors to parse warnings correctly.

* guix/scripts/lint.scm (emit-warning): Use 'format' instead of
  'warning', to avoid the "guix lint: " prefix in messages.
* tests/lint.scm (call-with-warnings): Indent.

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/lint.scm b/tests/lint.scm
index f6dae47ca6..56558c904f 100644
--- a/tests/lint.scm
+++ b/tests/lint.scm
@@ -39,10 +39,10 @@
            (home-page #f) (license #f) ))
 
 (define (call-with-warnings thunk)
-       (let ((port (open-output-string)))
-         (parameterize ((guix-warning-port port))
-           (thunk))
-         (get-output-string port)))
+  (let ((port (open-output-string)))
+    (parameterize ((guix-warning-port port))
+      (thunk))
+    (get-output-string port)))
 
 (test-assert "synopsis: ends with a period"
   (->bool