git-p4: Unset P4DIFF environment variable when using 'p4 -du diff'

diff --git a/git-gui/lib/about.tcl b/git-gui/lib/about.tcl
index 47be8eb97ab79188bba8dca18f3784327302ba9a..241ab892cd5b731f07571acf7a0ca3150a763f4f 100644 (file)
--- a/git-gui/lib/about.tcl
+++ b/git-gui/lib/about.tcl
@@ -41,7 +41,8 @@ proc do_about {} {
                append v "Tcl version $tcl_patchLevel"
                append v ", Tk version $tk_patchLevel"
        }
-       if {[info exists ui_comm_spell]} {
+       if {[info exists ui_comm_spell]
+               && [$ui_comm_spell version] ne {}} {
                append v "\n"
                append v [$ui_comm_spell version]
        }