install script does not recognize '--prefix' option but must

[VladRassokhin]

I'm running install --prefix "$(pwd)/inst from rvm sources and output is:

Unrecognized option: --prefix

  Usage:

    ./install [options]

  options:

    --auto    : Automatically update shell profile files.

                --prefix  : Installation prefix directory (rvm_path).

    --help    : Display help/usage (this) message

    --version : display rvm package version

after viewing install sources i have created patch

diff --git a/scripts/install b/scripts/install
index 18a153d..58e1320 100755
--- a/scripts/install
+++ b/scripts/install
@@ -73,6 +73,10 @@ do
       install_usage
       exit 0
       ;;
+    (--prefix)
+      DESTDIR="$1"
+      shift
+      ;;
     (*)
       echo "Unrecognized option: $token"
       install_usage

but it's doesn't help:

vlad@unit-421 /media/devel/rvm $ ./install --prefix "`pwd`/inst"

Upgrading the RVM installation in /home/vlad/.rvm/
^C

Killed because i don't want to update my installation. I just want to install rvm into specific folder.