Add support for pyadb to setup_adb.sh

platform_tools/android/bin/utils/setup_adb.sh

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 UTIL_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
+if [ $PYADB ] && [ -a "$PYADB" ]; then
+  echo "Python ADB detected, going to use that"
+  ADB="python ${PYADB}"
+  return
+fi
+
 if [ "$(which adb)" != "" ]; then
     ADB="$(which adb)"
 elif [ -d "$ANDROID_SDK_ROOT" ]; then
     ADB="${ANDROID_SDK_ROOT}/platform-tools/adb"
 else
   echo $ANDROID_SDK_ROOT
   echo "No ANDROID_SDK_ROOT set (check that android_setup.sh was properly sourced)"
   exit 1
 fi
 
@@ skipping 11 matching lines @@
 # get the version string as an array, use just the version numbers
 ADB_VERSION="$($ADB version)"
 ADB_VERSION=($ADB_VERSION)
 ADB_VERSION=${ADB_VERSION[4]}
 
 if [[ "$ADB_REQUIRED" != *"$ADB_VERSION"* ]]; then
   echo "WARNING: Your ADB version is out of date!"
   echo "  Expected ADB Version: ${ADB_REQUIRED}"
   echo "  Actual ADB Version: ${ADB_VERSION}"
 fi