gitk: Show modified files with separate work tree

"git rev-parse --is-inside-work-tree" is currently used to determine
whether to show modified files in gitk (the red and green fake
commits). This does not work if the current directory is not inside
the work tree, as can be the case e.g. if GIT_WORK_TREE is
set. Instead, check if the repository is not bare and that we are not
inside the .git directory.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -9,6 +9,11 @@ exec wish "$0" -- "$@"
 
 package require Tk
 
+proc hasworktree {} {
+    return [expr {[exec git rev-parse --is-bare-repository] == "false" &&
+		  [exec git rev-parse --is-inside-git-dir] == "false"}]
+}
+
 # A simple scheduler for compute-intensive stuff.
 # The aim is to make sure that event handlers for GUI actions can
 # run at least every 50-100 ms.  Unfortunately fileevent handlers are
@@ -459,11 +464,11 @@ proc updatecommits {} {
     global viewactive viewcomplete tclencoding
     global startmsecs showneartags showlocalchanges
     global mainheadid viewmainheadid viewmainheadid_orig pending_select
-    global isworktree
+    global hasworktree
     global varcid vposids vnegids vflags vrevs
     global show_notes
 
-    set isworktree [expr {[exec git rev-parse --is-inside-work-tree] == "true"}]
+    set hasworktree [hasworktree]
     rereadrefs
     set view $curview
     if {$mainheadid ne $viewmainheadid_orig($view)} {
@@ -5024,9 +5029,9 @@ proc dohidelocalchanges {} {
 # spawn off a process to do git diff-index --cached HEAD
 proc dodiffindex {} {
     global lserial showlocalchanges vfilelimit curview
-    global isworktree
+    global hasworktree
 
-    if {!$showlocalchanges || !$isworktree} return
+    if {!$showlocalchanges || !$hasworktree} return
     incr lserial
     set cmd "|git diff-index --cached HEAD"
     if {$vfilelimit($curview) ne {}} {
@@ -11633,9 +11638,9 @@ set stopped 0
 set stuffsaved 0
 set patchnum 0
 set lserial 0
-set isworktree [expr {[exec git rev-parse --is-inside-work-tree] == "true"}]
+set hasworktree [hasworktree]
 set cdup {}
-if {$isworktree} {
+if {[expr {[exec git rev-parse --is-inside-work-tree] == "true"}]} {
     set cdup [exec git rev-parse --show-cdup]
 }
 set worktree [exec git rev-parse --show-toplevel]