git-gui: Warn users before making an octopus merge

diff --git a/git-gui.sh b/git-gui.sh
index f6c6d44357502672bca34be983eda8a5b29221c8..dd8a408c644ad190cf69aa60f8d62a6a2ed625be 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -2886,6 +2886,19 @@ proc start_local_merge_action {w} {
                set unit branch
        } elseif {$revcnt <= 15} {
                set unit branches
+
+               if {[tk_dialog \
+               $w.confirm_octopus \
+               [wm title $w] \
+               "Use octopus merge strategy?
+
+You are merging $revcnt branches at once.  This requires using the octopus merge driver, which may not succeed if there are file-level conflicts.
+" \
+               question \
+               0 \
+               {Cancel} \
+               {Use octopus} \
+               ] != 1} return
        } else {
                tk_messageBox \
                        -icon error \