gitk: Fix bug causing incorrect ref list contents when switching view

If the view we're switching to hadn't been read in, we hit an early
return in showview which meant we didn't update the ref list window.

Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -2007,6 +2007,7 @@ proc showview {n} {
     .bar.view entryconf Edit* -state [expr {$n == 0? "disabled": "normal"}]
     .bar.view entryconf Delete* -state [expr {$n == 0? "disabled": "normal"}]
 
+    run refill_reflist
     if {![info exists viewdata($n)]} {
 	if {$selid ne {}} {
 	    set pending_select $selid
@@ -2070,7 +2071,6 @@ proc showview {n} {
     } elseif {$numcommits == 0} {
 	show_status "No commits selected"
     }
-    run refill_reflist
 }
 
 # Stuff relating to the highlighting facility