fix vm install

Author: blink1073

.evergreen/scripts/install-dependencies.sh

@@ -3,14 +3,15 @@
 set -eu
 
 HERE=$(dirname ${BASH_SOURCE:-$0})
+CURRENT=$(pwd)
 pushd "$(dirname "$(dirname $HERE)")" > /dev/null
 
 # Source the env files to pick up common variables.
 if [ -f $HERE/env.sh ]; then
   . $HERE/env.sh
 fi
 
-_BIN_DIR=${PYMONGO_BIN_DIR:-.}
+_BIN_DIR=${PYMONGO_BIN_DIR:-$CURRENT}
 
 # Helper function to pip install a dependency using a temporary python env.
 function _pip_install() {