git-am: use apply --cached

Now 'git apply' can apply patch without working tree, preparation
of pristine preimage and postimage trees that are done when falling
back on 3-way merge by "git am" can do so without temporary files.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-am.sh b/git-am.sh
index 507ae4d..f50dff2 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -55,46 +55,12 @@ fall_back_3way () {
        GIT_INDEX_FILE="$dotest/patch-merge-tmp-index" \
        git-write-tree >"$dotest/patch-merge-base+" &&
        # index has the base tree now.
-       (
-           cd "$dotest/patch-merge-tmp-dir" &&
-           GIT_INDEX_FILE="../patch-merge-tmp-index" \
-           GIT_OBJECT_DIRECTORY="$O_OBJECT" \
-           git-apply $binary --index <../patch
-        )
+       GIT_INDEX_FILE="$dotest/patch-merge-tmp-index" \
+       git-apply $binary --cached <"$dotest/patch"
     then
        echo Using index info to reconstruct a base tree...
        mv "$dotest/patch-merge-base+" "$dotest/patch-merge-base"
        mv "$dotest/patch-merge-tmp-index" "$dotest/patch-merge-index"
-    else
-       # Otherwise, try nearby trees that can be used to apply the
-       # patch.
-       (
-           N=10
-
-           # Hoping the patch is against our recent commits...
-           git-rev-list --max-count=$N HEAD
-
-           # or hoping the patch is against known tags...
-           git-ls-remote --tags .
-       ) |
-       while read base junk
-       do
-           # See if we have it as a tree...
-           git-cat-file tree "$base" >/dev/null 2>&1 || continue
-
-           rm -fr "$dotest"/patch-merge-* &&
-           mkdir "$dotest/patch-merge-tmp-dir" || break
-           (
-               cd "$dotest/patch-merge-tmp-dir" &&
-               GIT_INDEX_FILE=../patch-merge-tmp-index &&
-               GIT_OBJECT_DIRECTORY="$O_OBJECT" &&
-               export GIT_INDEX_FILE GIT_OBJECT_DIRECTORY &&
-               git-read-tree "$base" &&
-               git-apply $binary --index &&
-               mv ../patch-merge-tmp-index ../patch-merge-index &&
-               echo "$base" >../patch-merge-base
-           ) <"$dotest/patch"  2>/dev/null && break
-       done
     fi
 
     test -f "$dotest/patch-merge-index" &&