Generalize python_git_runner for use in non-git scripts.

python_runner.sh

+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+## This file is designed to be sourced from a bash script whose name takes the
+## form 'command-name'. This script will then instead invoke
+## '[depot_tools]/command_name.py' correctly under mingw as well
+## as posix-ey systems, passing along all other command line flags.
+
+## Example:
+## echo ". python_runner.sh" > git-foo-command
+## ./git-foo-command  #=> runs `python git_foo_command.py`
+
+## Constants
+PYTHONDONTWRITEBYTECODE=1
+
+## "Input parameters".
+# If set before the script is sourced, then we'll use the pre-set values.
+#
+# SCRIPT defaults to the basename of $0, with dashes replaced with underscores
+
+# "$0" can have several different formats depending on how the script was called
+# and the environment being used, including having different formats even in the
+# same environment (e.g. in msys, 'git cl' causes $0 to have a Windows-style
+# path, but calling 'git-cl' results in a POSIX-style path), so don't assume a
+# particular format.
+# First try to split it using Windows format ...
+DEPOT_TOOLS="${0%\\*}"
+if [[ "$DEPOT_TOOLS" = "$0" ]]; then
+  # If that didn't work, try POSIX format ...
+  DEPOT_TOOLS="${0%/*}"
+  if [[ "$DEPOT_TOOLS" = "$0" ]]; then
+    # Sometimes commands will run with no path (e.g. a git command run from
+    # within the depot_tools dir itself). In that case, treat it as if run like:
+    # "./command"
+    DEPOT_TOOLS="."
+    BASENAME="$0"
+  else
+    BASENAME="${0##*/}"
+  fi
+else
+  BASENAME="${0##*\\}"
+fi
+SCRIPT="${SCRIPT-${BASENAME//-/_}.py}"
+
+if [[ -e "$DEPOT_TOOLS/python.bat" && $OSTYPE = msys ]]; then
+  cmd.exe //c "$DEPOT_TOOLS\\python.bat" "$DEPOT_TOOLS\\$SCRIPT" "$@"
+else
+  exec "$DEPOT_TOOLS/$SCRIPT" "$@"
+fi