erratic behavior commit --allow-empty

Hi

I have noticed an erratic behavior of git commit --allow-empty: sometimes it creates a new commit, but sometimes not. I have executed two times the following script, emptycommit:

#!/bin/bash set -x rm -rf local mkdir local cd local git init echo "aaa" >f1 git add f1 git commit -m A git checkout --orphan feature git commit -m A --allow-empty git rev-list --all --pretty=oneline

This is the log of the first execution:

$ emptycommit
+ rm -rf local
+ mkdir local
+ cd local
+ git init
Initialized empty Git repository in d:/gtest/local/.git/
+ echo aaa
+ git add f1
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
+ git commit -m A
[master (root-commit) 07e7d37] A
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
 1 file changed, 1 insertion(+)
 create mode 100644 f1
+ git checkout --orphan feature
Switched to a new branch 'feature'
+ git commit -m A --allow-empty
[feature (root-commit) 2297c4e] A
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
 1 file changed, 1 insertion(+)
 create mode 100644 f1
+ git rev-list --all --pretty=oneline
2297c4e34ec27f3cdeca8c0dcdcd61b4a079f411 A
07e7d379c2339ed375ed4903f6196d627367b7bf A

This is the log of the second execution:

$ emptycommit
+ rm -rf local
+ mkdir local
+ cd local
+ git init
Initialized empty Git repository in d:/gtest/local/.git/
+ echo aaa
+ git add f1
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
+ git commit -m A
[master (root-commit) 1b86218] A
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
 1 file changed, 1 insertion(+)
 create mode 100644 f1
+ git checkout --orphan feature
Switched to a new branch 'feature'
+ git commit -m A --allow-empty
[feature (root-commit) 1b86218] A
warning: LF will be replaced by CRLF in f1.
The file will have its original line endings in your working directory.
 1 file changed, 1 insertion(+)
 create mode 100644 f1
+ git rev-list --all --pretty=oneline
1b8621851f6ae2943347da655661e9d5dc978208 A

The script has been run on Windows 7 with git version 1.7.11.msysgit.1

-Angelo