Omit empty sections.

* magit.el (magit-insert-section): Insert final newline only when
inserted output is not empty.  Delete title when it is.

magit.el

@@ -280,15 +280,16 @@ Many Magit faces inherit from this one by default."
     (if title
 	(insert (propertize title 'face 'magit-section-title) "\n"))
     (let* ((beg (point))
-	   (status (apply 'call-process cmd nil t nil args))
-	   (end (point)))
-      (insert "\n")
+	   (status (apply 'call-process cmd nil t nil args)))
       (put-text-property section-beg (point) 'magit-section (list section))
       (if washer
 	  (save-restriction
 	    (narrow-to-region beg (point))
 	    (funcall washer status)
-	    (goto-char (point-max)))))))
+	    (goto-char (point-max))))
+      (if (/= beg (point))
+	  (insert "\n")
+	(delete-region section-beg (point))))))
 
 (defun magit-section-head (section n)
   (if (<= (length section) n)

magit.texi

@@ -93,8 +93,9 @@ the status buffer in this way after saving a file in Emacs.
 
 The header at the top of the status buffer shows a short summary of
 the repository state: where it is located, which branch is checked
-out, etc.  Below the header are three or four sections that show
-details about the working tree and the staging area.
+out, etc.  Below the header are up to four sections that show details
+about the working tree and the staging area.  Only sections that are
+not empty are shown.
 
 The first of these sections lists @emph{Untracked files}.  These are
 the files that are present in your working tree but are not known to