(history) move git-timemachine init to pre-entry hook

This still ends up setting the evil state in the original buffer rather
than the timemachine buffer, though the evil state is set post-entry.
Not sure why.

Note the evil state is purely for UI feedback purposes and has no
functional effect.

rigpa-history-mode.el

@@ -50,10 +50,13 @@
   :lighter " history"
   :group 'rigpa)
 
+(defun rigpa--on-history-mode-pre-entry ()
+  "Pre-entry"
+  (unless git-timemachine-mode
+    (git-timemachine)))
+
 (defun rigpa--on-history-mode-entry ()
   "Actions to take upon entry into history mode."
-  (unless git-timemachine-mode
-    (git-timemachine))
   ;; TODO: probably do this via a standard internal
   ;; rigpa hook in mode registration
   (evil-history-state))

rigpa.el

@@ -271,6 +271,7 @@
                        :post-entry #'rigpa--on-activity-mode-entry
                        :post-exit #'rigpa--on-activity-mode-post-exit)
   (rigpa-register-mode chimera-history-mode
+                       :pre-entry #'rigpa--on-history-mode-pre-entry
                        :post-entry #'rigpa--on-history-mode-entry
                        :post-exit #'rigpa--on-history-mode-post-exit)
   (rigpa-register-mode chimera-tab-mode