Isolate depot_tools update into a separate script.

gclient

Index: gclient
diff --git a/gclient b/gclient
index 34478dc29db5e5f9dfc5d8d1cbc01f0088558dc0..19cc68dae9f9ce87112e4a66a667b6d545b809a7 100755
--- a/gclient
+++ b/gclient
@@ -3,68 +3,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# This script will try to sync the bootstrap directories and then defer control.
-
 base_dir=$(dirname "$0")
 
-# Test git and git --version.
-function test_git {
-  local GITV="$(git --version)" || {
-    echo "git isn't installed, please install it"
-    exit 1
-  }
-
-  GITV="${GITV##* }"          # Only examine last word (i.e. version number)
-  local GITD=( ${GITV//./ } ) # Split version number into decimals
-  if ((GITD[0] < 1 || (GITD[0] == 1 && GITD[1] < 6) )); then
-    echo "git version is ${GITV}, please update to a version later than 1.6"
-    exit 1
-  fi
-}
-
-# Test git svn and git svn --version.
-function test_git_svn {
-  local GITV="$(git svn --version)" || {
-    echo "git-svn isn't installed, please install it"
-    exit 1
-  }
-
-  GITV="${GITV#* version }"   # git svn --version has extra output to remove.
-  GITV="${GITV% (svn*}"
-  local GITD=( ${GITV//./ } ) # Split version number into decimals
-  if ((GITD[0] < 1 || (GITD[0] == 1 && GITD[1] < 6) )); then
-    echo "git version is ${GITV}, please update to a version later than 1.6"
-    exit 1
-  fi
-}
-
-
-# Update git checkouts prior the cygwin check, we don't want to use msysgit.
-if [ "X$DEPOT_TOOLS_UPDATE" != "X0" -a -e "$base_dir/.git" ]
-then
-  cd $base_dir
-  test_git_svn
-  # work around a git-svn --quiet bug
-  OUTPUT=`git svn rebase -q -q`
-  if [[ ! "$OUTPUT" =~ Current.branch ]]; then
-    echo $OUTPUT
-  fi
-  cd - > /dev/null
-fi
-
-# Use the batch file as an entry point if on cygwin.
-if [ "${OSTYPE}" = "cygwin" -a "${TERM}" != "xterm" ]; then
-   ${base_dir}/gclient.bat "$@"
-   exit
-fi
-
-
-# We're on POSIX (not cygwin). We can now safely look for svn checkout.
-if [ "X$DEPOT_TOOLS_UPDATE" != "X0" -a -e "$base_dir/.svn" ]
-then
-  # Update the bootstrap directory to stay up-to-date with the latest
-  # depot_tools.
-  svn -q up "$base_dir"
-fi
+"$base_dir"/update_depot_tools
 
 exec python "$base_dir/gclient.py" "$@"