[PATCH] Do not create bogus branch from flag to git branch

[Amos Waterland <apw@rossby.metr.ou.edu>]

If you run `git branch --help', you will unexpectedly have created a new
branch named "--help".  This simple patch adds logic and a usage
statement to catch this and similar problems, and adds a testcase for it.

Signed-off-by: Amos Waterland <apw@rossby.metr.ou.edu>

---

 git-branch-script |   16 ++++++++++++++++
 t/t3200-branch.sh |   27 +++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 0 deletions(-)
 create mode 100755 t/t3200-branch.sh

09dc220283888eabd4dbb3ca647d13de6d6c876e
diff --git a/git-branch-script b/git-branch-script
--- a/git-branch-script
+++ b/git-branch-script
@@ -2,6 +2,16 @@
 
 . git-sh-setup-script || die "Not a git archive"
 
+usage () {
+    echo >&2 "usage: $(basename $0)"' [<branchname> [start-point]]
+
+If no arguments, show available branches and mark current branch with a star.
+If one argument, create a new branch <branchname> based off of current HEAD.
+If two arguments, create a new branch <branchname> based off of <start-point>.
+'
+    exit 1
+}
+
 case "$#" in
 0)
 	headref=$(readlink "$GIT_DIR/HEAD" | sed -e 's|^refs/heads/||')
@@ -25,6 +35,12 @@ case "$#" in
 	head="$2^0" ;;
 esac
 branchname="$1"
+
+case "$branchname" in
+-*)
+	usage;;
+esac
+
 rev=$(git-rev-parse --verify "$head") || exit
 
 [ -e "$GIT_DIR/refs/heads/$branchname" ] && die "$branchname already exists"
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
new file mode 100755
--- /dev/null
+++ b/t/t3200-branch.sh
@@ -0,0 +1,27 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Amos Waterland
+#
+
+test_description='git branch --foo should not create bogus branch
+
+This test runs git branch --help and checks that the argument is properly
+handled.  Specifically, that a bogus branch is not created.
+'
+. ./test-lib.sh
+
+test_expect_success \
+    'prepare an trivial repository' \
+    'echo Hello > A &&
+     git update-cache --add A &&
+     git commit -m "Initial commit."'
+
+test_expect_failure \
+    'git branch --help should return error code' \
+    'git branch --help'
+
+test_expect_failure \
+    'git branch --help should not have created a bogus branch' \
+    'test -f .git/refs/heads/--help'
+
+test_done