[gnome-photos] application: Clarify a comment

[Debarshi Ray <debarshir src gnome org>]

commit 0de40ffa2db4c39167b8b2d925540e106dd2baec
Author: Debarshi Ray <debarshir gnome org>
Date:   Sun Jul 24 13:26:30 2016 +0200

    application: Clarify a comment

 src/photos-application.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/photos-application.c b/src/photos-application.c
index bf1c5be..9d6e3c1 100644
--- a/src/photos-application.c
+++ b/src/photos-application.c
@@ -756,7 +756,11 @@ photos_application_edit_cancel_process (GObject *source_object, GAsyncResult *re
       g_error_free (error);
     }
 
-  /* Go back, no matter what. */
+  /* Go back, no matter what. The revert can only fail in very
+   * exceptional circumstances (currently I don't know of any). So,
+   * if and when it fails, we don't want to be stuck inside the EDIT
+   * mode.
+   */
   photos_mode_controller_go_back (self->state->mode_cntrlr);
   g_application_release (G_APPLICATION (self));
 }