Make drover works in cygwin.

drover

Index: drover
===================================================================
--- drover	(revision 30271)
+++ drover	(working copy)
@@ -6,22 +6,21 @@
 # This script will try to sync the bootstrap directories and then defer control.
 
 base_dir=$(dirname "$0")
-script=drover
 
 # Use the batch file as an entry point if on cygwin.
 if [ "${OSTYPE}" = "cygwin" -a "${TERM}" != "xterm" ]; then
-   ${base_dir}/$drover.bat "$@"
+   ${base_dir}/drover.bat "$@"
    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" ]
+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 "$base_dir"
+  svn -q up "${base_dir}"
 fi
 
-exec python "$base_dir/$script.py" "$@"
+exec python "${base_dir}/drover.py" "$@"