Leave merge failures in the filesystem

This changes how we handle merges: if a automated merge
fails, we will leave the index as a clean entry pointing
to the original branch, and leave the actual file _dirty_
the way the "merge" program left it.

You can then just do "git-diff-files -p" to see what the
merge conflicts did, fix them up, and commit the end result.

NOTE NOTE NOTE! Do _not_ use "git commit" to commit such
a merge. It won't set the parents right. I'll need to fix
that. In the meantime, you'd need to merge using

	git-commit-tree $(git-write) -p HEAD -p MERGE_HEAD

or something like that by hand.

diff --git a/git-merge-one-file-script b/git-merge-one-file-script
index 3e128c6..62cbb2a 100755 (executable)
--- a/git-merge-one-file-script
+++ b/git-merge-one-file-script
@@ -19,22 +19,25 @@ case "${1:-.}${2:-.}${3:-.}" in
 # Deleted in both.
 #
 "$1..")
-       echo "ERROR: $4 is removed in both branches."
-       echo "ERROR: This is a potential rename conflict."
-       exit 1;;
+       echo "WARNING: $4 is removed in both branches."
+       echo "WARNING: This is a potential rename conflict."
+       exec git-update-cache --remove -- "$4" ;;
 #
 # Deleted in one and unchanged in the other.
 #
 "$1.." | "$1.$1" | "$1$1.")
        echo "Removing $4"
-       exec git-update-cache --force-remove "$4" ;;
+       rm -f -- "$4"
+       exec git-update-cache --remove -- "$4" ;;
 #
 # Added in one.
 #
 ".$2." | "..$3" )
        case "$6$7" in *7??) mode=+x;; *) mode=-x;; esac
        echo "Adding $4 with perm $mode."
-       exec git-update-cache --add --cacheinfo "$6$7" "$2$3" "$4" ;;
+       git-cat-file blob "$2$3" > "$4"
+       chmod $mode -- "$4"
+       exec git-update-cache --add -- "$4" ;;
 #
 # Added in both (check for same permissions).
 #
@@ -46,7 +49,9 @@ case "${1:-.}${2:-.}${3:-.}" in
        fi
        case "$6" in *7??) mode=+x;; *) mode=-x;; esac
        echo "Adding $4 with perm $mode"
-       exec git-update-cache --add --cacheinfo "$6" "$2" "$4" ;;
+       git-cat-file blob "$2" > "$4"
+       chmod $mode -- "$4"
+       exec git-update-cache --add -- "$4" ;;
 #
 # Modified in both, but differently.
 #
@@ -55,19 +60,21 @@ case "${1:-.}${2:-.}${3:-.}" in
        orig=`git-unpack-file $1`
        src1=`git-unpack-file $2`
        src2=`git-unpack-file $3`
-       merge "$src2" "$orig" "$src1"
+       merge -p "$src1" "$orig" "$src2" > "$4"
        ret=$?
+       rm -f -- "$orig" "$src1" "$src2"
        if [ "$6" != "$7" ]; then
                echo "ERROR: Permissions $5->$6->$7 don't match."
+               ret=1
        fi
        if [ $ret -ne 0 ]; then
-               echo "ERROR: Leaving conflict merge in $src2."
+               # Reset the index to the first branch, making
+               # git-diff-file useful
+               git-update-cache --add --cacheinfo "$6" "$2" "$4"
+               echo "ERROR: Merge conflict in $4."
                exit 1
        fi
-       sha1=`git-write-blob "$src2"` || {
-               echo "ERROR: Leaving conflict merge in $src2."
-       }
-       exec git-update-cache --add --cacheinfo "$6" $sha1 "$4" ;;
+       exec git-update-cache --add -- "$4" ;;
 *)
        echo "ERROR: Not handling case $4: $1 -> $2 -> $3" ;;
 esac