am --skip: support skipping while on unborn branch

diff --git a/git-am.sh b/git-am.sh
index ee61a77d717a7210a1cf614914ab62788fd5e4fc..e0d067c00e6a4405ea59ab51c5e1ce3fbaf80b0c 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -68,6 +68,8 @@ then
        cmdline="$cmdline -3"
 fi
 
+empty_tree=4b825dc642cb6eb9a060e54bf8d69288fbee4904
+
 sq () {
        git rev-parse --sq-quote "$@"
 }
@@ -176,7 +178,8 @@ It does not apply to blobs recorded in its index.")"
     then
            GIT_MERGE_VERBOSITY=0 && export GIT_MERGE_VERBOSITY
     fi
-    git-merge-recursive $orig_tree -- HEAD $his_tree || {
+    our_tree=$(git rev-parse --verify -q HEAD || echo $empty_tree)
+    git-merge-recursive $orig_tree -- $our_tree $his_tree || {
            git rerere $allow_rerere_autoupdate
            die "$(gettext "Failed to merge in the changes.")"
     }
@@ -492,10 +495,11 @@ then
                ;;
        t,)
                git rerere clear
-               git read-tree --reset -u HEAD HEAD
-               orig_head=$(cat "$GIT_DIR/ORIG_HEAD")
-               git reset HEAD
-               git update-ref ORIG_HEAD $orig_head
+               head_tree=$(git rev-parse --verify -q HEAD || echo $empty_tree) &&
+               git read-tree --reset -u $head_tree $head_tree &&
+               index_tree=$(git write-tree) &&
+               git read-tree -m -u $index_tree $head_tree
+               git read-tree $head_tree
                ;;
        ,t)
                if test -f "$dotest/rebasing"