Having .git as a file it's also a valid situation

sys/install-rev.sh

@@ -11,7 +11,7 @@ gmake --help >/dev/null 2>&1
 
 # find root
 cd "$(dirname "$PWD/$0")" ; cd ..
-if [ -d .git ]; then
+if [ -e .git ]; then
 	echo git checkout "${REV}"
 	git checkout "${REV}"
 fi

sys/r2vm

@@ -69,7 +69,7 @@ Clone() {
 		exit 1
 	fi
 	cd radare2-${1}
-	if [ -d .git ]; then
+	if [ -e .git ]; then
 		git reset --hard $1 || exit 1
 		mv .git _git
 	fi

sys/user.sh

@@ -51,7 +51,7 @@ done
 
 # update
 if [ $WITHOUT_PULL -eq 0 ]; then
-	if [ -d .git ]; then
+	if [ -e .git ]; then
 		git branch | grep "^\* master" > /dev/null
 		if [ $? = 0 ]; then
 			echo "WARNING: Updating from remote repository"