Merge branch 'da/gitk-reload-tag-contents' of git://github.com/gitster/git

to get two commits from David Aguilar.

diff --combined gitk
index 1f412bb5e5376b69c69ef0a0b78660b6f8e53c27,6f24f53d217884607f1bf04c4b2f715cf6ad78ac..d93bd990a9d7fc9ad7c926e25f5d58f4e7514260
--- 1/gitk
--- 2/gitk
+++ b/gitk
@@@ -10599,7 -10599,7 +10599,7 @@@ proc movedhead {hid head} 
  }
  
  proc changedrefs {} {
-     global cached_dheads cached_dtags cached_atags
+     global cached_dheads cached_dtags cached_atags cached_tagcontent
      global arctags archeads arcnos arcout idheads idtags
  
      foreach id [concat [array names idheads] [array names idtags]] {
@@@ -10611,6 -10611,7 +10611,7 @@@
            }
        }
      }
+     catch {unset cached_tagcontent}
      catch {unset cached_dtags}
      catch {unset cached_atags}
      catch {unset cached_dheads}
@@@ -10663,7 -10664,7 +10664,7 @@@ proc listrefs {id} 
  }
  
  proc showtag {tag isnew} {
-     global ctext tagcontents tagids linknum tagobjid
+     global ctext cached_tagcontent tagids linknum tagobjid
  
      if {$isnew} {
        addtohistory [list showtag $tag 0] savectextpos
@@@ -10672,13 -10673,13 +10673,13 @@@
      clear_ctext
      settabs 0
      set linknum 0
-     if {![info exists tagcontents($tag)]} {
+     if {![info exists cached_tagcontent($tag)]} {
        catch {
-            set tagcontents($tag) [exec git cat-file tag $tag]
+            set cached_tagcontent($tag) [exec git cat-file tag $tag]
        }
      }
-     if {[info exists tagcontents($tag)]} {
-       set text $tagcontents($tag)
+     if {[info exists cached_tagcontent($tag)]} {
+       set text $cached_tagcontent($tag)
      } else {
        set text "[mc "Tag"]: $tag\n[mc "Id"]:  $tagids($tag)"
      }
@@@ -11532,11 -11533,6 +11533,11 @@@ if {[catch {package require Tk 8.4} err
      exit 1
  }
  
 +# Unset GIT_TRACE var if set
 +if { [info exists ::env(GIT_TRACE)] } {
 +    unset ::env(GIT_TRACE)
 +}
 +
  # defaults...
  set wrcomcmd "git diff-tree --stdin -p --pretty"