Documentation: cloning to empty directory is allowed

diff --git a/git-am.sh b/git-am.sh
index d3390755fc687a611e89320a7bbfb4ead512c863..6d1848b6cce89e4953a3ca6e1b2e6e1611277a4a 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -36,6 +36,13 @@ cd_to_toplevel
 git var GIT_COMMITTER_IDENT >/dev/null ||
        die "You need to set your committer info first"
 
+if git rev-parse --verify -q HEAD >/dev/null
+then
+       HAS_HEAD=yes
+else
+       HAS_HEAD=
+fi
+
 sq () {
        for sqarg
        do
@@ -290,16 +297,26 @@ else
                : >"$dotest/rebasing"
        else
                : >"$dotest/applying"
-               git update-ref ORIG_HEAD HEAD
+               if test -n "$HAS_HEAD"
+               then
+                       git update-ref ORIG_HEAD HEAD
+               else
+                       git update-ref -d ORIG_HEAD >/dev/null 2>&1
+               fi
        fi
 fi
 
 case "$resolved" in
 '')
-       files=$(git diff-index --cached --name-only HEAD --) || exit
+       case "$HAS_HEAD" in
+       '')
+               files=$(git ls-files) ;;
+       ?*)
+               files=$(git diff-index --cached --name-only HEAD --) ;;
+       esac || exit
        if test "$files"
        then
-               : >"$dotest/dirtyindex"
+               test -n "$HAS_HEAD" && : >"$dotest/dirtyindex"
                die "Dirty index: cannot apply patches (dirty: $files)"
        fi
 esac
@@ -541,18 +558,20 @@ do
        fi
 
        tree=$(git write-tree) &&
-       parent=$(git rev-parse --verify HEAD) &&
        commit=$(
                if test -n "$ignore_date"
                then
                        GIT_AUTHOR_DATE=
                fi
+               parent=$(git rev-parse --verify -q HEAD) ||
+               echo >&2 "applying to an empty history"
+
                if test -n "$committer_date_is_author_date"
                then
                        GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"
                        export GIT_COMMITTER_DATE
                fi &&
-               git commit-tree $tree -p $parent <"$dotest/final-commit"
+               git commit-tree $tree ${parent:+-p} $parent <"$dotest/final-commit"
        ) &&
        git update-ref -m "$GIT_REFLOG_ACTION: $FIRSTLINE" HEAD $commit $parent ||
        stop_here $this