New update method

- backup the packages to be updated
- then delete them
- the user restart emacs and spacemacs will install the last version

Fixes some update errors related to byte-compilation like the one
which affected the powerline (void variable left)

This commit also adds some page break for clarity

core/core-configuration-layer.el

@@ -449,6 +449,7 @@ If PRE is non nil then `layer-pre-extensions' is read instead of
 (defun configuration-layer/update-packages ()
   "Upgrade elpa packages"
   (interactive)
+  (spacemacs/insert-page-break)
   (spacemacs/append-to-buffer
    "\nUpdating Spacemacs... (for now only ELPA packages are updated)\n")
   (spacemacs/append-to-buffer
@@ -472,7 +473,7 @@ If PRE is non nil then `layer-pre-extensions' is read instead of
              "Packages update has been cancelled.\n")
           ;; backup the package directory and construct an alist
           ;; variable to be cached for easy update and rollback
-          (spacemacs/replace-last-line-of-buffer
+          (spacemacs/append-to-buffer
            "--> performing backup of package(s) to update...\n" t)
           (spacemacs//redisplay)
           (dolist (pkg update-packages)
@@ -491,25 +492,14 @@ If PRE is non nil then `layer-pre-extensions' is read instead of
           (dolist (pkg update-packages)
             (setq upgraded-count (1+ upgraded-count))
             (spacemacs/replace-last-line-of-buffer
-             (format "--> updating package %s... [%s/%s]"
+             (format "--> preparing update of package %s... [%s/%s]"
                      pkg upgraded-count upgrade-count) t)
             (spacemacs//redisplay)
-            (configuration-layer//package-delete pkg)
-            (condition-case err (package-install pkg)
-              ('error
-               (message (format
-                         (concat "An error occurred during the update of "
-                                 "this package %s, retrying one more time...")
-                         err))
-               (package-install pkg)))
-            (when (version< emacs-version "24.3.50")
-              ;; explicitly force activation
-              (setq package-activated-list (delq pkg package-activated-list))
-              (configuration-layer//activate-package pkg)))
+            (configuration-layer//package-delete pkg))
           (spacemacs/append-to-buffer
-           (format "\n--> %s packages updated.\n" upgraded-count))
+           (format "\n--> %s package(s) to be updated.\n" upgraded-count))
           (spacemacs/append-to-buffer
-           "\nEmacs has to be restarted for the changes to take effect.\n")
+           "\nEmacs has to be restarted to actually install the new packages.\n")
           (spacemacs//redisplay))
       (spacemacs/append-to-buffer "--> All packages are up to date.\n")
       (spacemacs//redisplay))))
@@ -539,6 +529,7 @@ to select one."
         (when candidates
           (ido-completing-read "Rollback slots (most recent are first): "
                                candidates))))))
+  (spacemacs/insert-page-break)
   (if (not slot)
       (message "No rollback slot available.")
     (string-match "^\\(.+?\\)\s.*$" slot)

core/core-spacemacs-buffer.el

@@ -112,6 +112,10 @@ buffer, right justified."
   "Display MSG in message prepended with '(Spacemacs)'."
   (message "(Spacemacs) %s" (apply 'format msg args)))
 
+(defun spacemacs/insert-page-break ()
+  "Insert a page break line in spacemacs buffer."
+  (spacemacs/append-to-buffer "\n\n\n"))
+
 (defun spacemacs/append-to-buffer (msg &optional messagebuf)
   "Append MSG to spacemacs buffer. If MESSAGEBUF is not nil then MSG is
  also written in message buffer."
@@ -195,7 +199,7 @@ buffer, right justified."
           (list-separator "\n\n"))
       (goto-char (point-max))
       (page-break-lines-mode)
-      (spacemacs/append-to-buffer "\n\n\n")
+      (spacemacs/insert-page-break)
       (mapc (lambda (el)
               (cond
                ((eq el 'recents)

core/core-spacemacs.el

@@ -348,7 +348,7 @@ version and the NEW version."
         ;; (vc-mode vc-mode)
        ;; "  " mode-line-modes mode-line-misc-info mode-line-end-spaces
        (spacemacs/set-mode-line
-        (format (concat "%s errors at startup! "
+        (format (concat "%s error(s) at startup! "
                         "Spacemacs may not be able to operate properly.")
                 configuration-layer-error-count))
        (force-mode-line-update))