cvsimport: Exit if an existing repository doesn't have the right branch.

diff --git a/git-cvsimport-script b/git-cvsimport-script
index 3f15772..1151fb8 100755 (executable)
--- a/git-cvsimport-script
+++ b/git-cvsimport-script
@@ -338,6 +338,11 @@ unless(-d $git_dir) {
        $last_branch = $opt_o;
        $orig_branch = "";
 } else {
+       -f "$git_dir/refs/head/$opt_o"
+               or die "Branch '$opt_o' does not exist.\n".
+                      "Either use the correct '-o branch' option,\n".
+                      "or import to a new repository.\n";
+
        $last_branch = basename(readlink("$git_dir/HEAD"));
        unless($last_branch) {
                warn "Cannot read the last branch name: $! -- assuming 'master'\n";