Remove hardcoding default branch as "master"

Default branch of repo could be "master", "main" or any names.
Stop hardcoding "master" as the default to clone and let "git"
decide it automatically.

scripts/install_plugins.sh

@@ -13,9 +13,14 @@ else # shell output functions
 fi
 
 clone() {
-	local plugin="$1"
-	cd "$(tpm_path)" &&
-		GIT_TERMINAL_PROMPT=0 git clone -b "$branch" --single-branch --recursive "$plugin" >/dev/null 2>&1
+	local plugin="$1" branch="$2"
+	if [ -n "$branch" ]; then
+		cd "$(tpm_path)" &&
+			GIT_TERMINAL_PROMPT=0 git clone -b "$branch" --single-branch --recursive "$plugin" >/dev/null 2>&1
+	else
+		cd "$(tpm_path)" &&
+			GIT_TERMINAL_PROMPT=0 git clone --single-branch --recursive "$plugin" >/dev/null 2>&1
+	fi
 }
 
 # tries cloning:
@@ -30,8 +35,7 @@ clone_plugin() {
 
 # clone plugin and produce output
 install_plugin() {
-	local plugin="$1"
-	local branch=`[ -z "$2" ] && echo "master" || echo "$2"`
+	local plugin="$1" branch="$2"
 	local plugin_name="$(plugin_name_helper "$plugin")"
 
 	if plugin_already_installed "$plugin"; then