Revert: Convert to double brackets

Staying POSIX compatible, don't use expanded test syntax from bash

flutterw

@@ -3,8 +3,8 @@
 ##############################################################################
 ##
 ##  Flutter start up script for UN*X
-##  Version: VERSION_PLACEHOLDER
-##  Date: DATE_PLACEHOLDER
+##  Version: fix_detached_head_fix
+##  Date: 2019-11-16 14:54:10
 ##
 ##  Use this flutter wrapper to bundle Flutter within your project to make
 ##  sure everybody builds with the same version.
@@ -20,7 +20,7 @@
 # Resolve links: $0 may be a link
 PRG="$0"
 # Need this for relative symlinks.
-while [[ -h "$PRG" ]]; do
+while [ -h "$PRG" ]; do
   ls=$(ls -ld "$PRG")
   link=$(expr "$ls" : '.*-> \(.*\)$')
   if expr "$link" : '/.*' >/dev/null; then
@@ -38,26 +38,26 @@ FLUTTER_SUBMODULE_NAME='.flutter'
 FLUTTER_DIR="$APP_HOME/$FLUTTER_SUBMODULE_NAME"
 
 # by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [[ "$(uname)" = "Darwin" ]] && [[ "$HOME" = "$PWD" ]]; then
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
   cd "$(dirname "$0")"
 fi
 
 # submodule starting with "-" are not initialized
 init_status=$(git submodule | grep "\ $FLUTTER_SUBMODULE_NAME$" | cut -c 1)
 
 # Fix not initialized flutter submodule
-if [[ "$init_status" = "-" ]]; then
+if [ "$init_status" = "-" ]; then
   echo "$FLUTTER_SUBMODULE_NAME submodule not initialized. Initializing..."
   git submodule update --init ${FLUTTER_SUBMODULE_NAME}
 fi
 
 # Detect detach HEAD and fix it. commands like upgrade expect a valid branch, not a detached HEAD
 FLUTTER_SYMBOLIC_REF=$(git -C ${FLUTTER_SUBMODULE_NAME} symbolic-ref -q HEAD)
-if [[ -z ${FLUTTER_SYMBOLIC_REF} ]]; then
+if [ -z ${FLUTTER_SYMBOLIC_REF} ]; then
   FLUTTER_REV=$(git -C ${FLUTTER_SUBMODULE_NAME} rev-parse HEAD)
   FLUTTER_CHANNEL=$(git config -f .gitmodules submodule.${FLUTTER_SUBMODULE_NAME}.branch)
 
-  if [[ -z $FLUTTER_CHANNEL ]]; then
+  if [ -z $FLUTTER_CHANNEL ]; then
     echo "Warning: Submodule '$FLUTTER_SUBMODULE_NAME' doesn't point to an official Flutter channel \
             (one of stable|beta|dev|master). './flutterw upgrade' will fail without a channel."
     echo "Fix this by adding a specific channel with:"
@@ -84,7 +84,7 @@ set -e
 
 # Post flutterw tasks. exit code from /bin/flutterw will be used as final exit
 FLUTTER_EXIT_STATUS=$?
-if [[ ${FLUTTER_EXIT_STATUS} -eq 0 ]]; then
+if [ ${FLUTTER_EXIT_STATUS} -eq 0 ]; then
 
   # ./flutterw channel CHANNEL
   if echo "$@" | grep -q "channel"; then