package: Use ~/.guix-profile as the default for --search-paths.

* guix/scripts/package.scm (search-path-environment-variables): Prefer
  %USER-ENVIRONMENT-DIRECTORY when it points to PROFILE.
  (display-search-paths): Use 3 spaces for indentation.

guix/scripts/package.scm

@@ -336,6 +336,14 @@ but ~a is available upstream~%")
 PACKAGES in PROFILE.  Use GETENV to determine the current settings and report
 only settings not already effective."
 
+  ;; Prefer ~/.guix-profile to the real profile directory name.
+  (let ((profile (if (and %user-environment-directory
+                          (false-if-exception
+                           (string=? (readlink %user-environment-directory)
+                                     profile)))
+                     %user-environment-directory
+                     profile)))
+
     ;; The search path info is not stored in the manifest.  Thus, we infer the
     ;; search paths from same-named packages found in the distro.
 
@@ -367,7 +375,7 @@ only settings not already effective."
            (search-paths (delete-duplicates
                           (append-map package-native-search-paths
                                       packages))))
-    (filter-map search-path-definition search-paths)))
+      (filter-map search-path-definition search-paths))))
 
 (define (display-search-paths packages profile)
   "Display the search path environment variables that may need to be set for