Resolve symlink paths before altering .tool-version files.

lib/commands/version_commands.sh

@@ -17,6 +17,11 @@ version_command() {
     file="$(pwd)/.tool-versions"
   fi
 
+  if [ -L "$file" ]; then
+      # Resolve file path if symlink
+      file="$(resolve_symlink "$file")"
+  fi
+
   check_if_plugin_exists "$plugin"
 
   local version
@@ -24,6 +29,7 @@ version_command() {
     check_if_version_exists "$plugin" "$version"
   done
 
+
   if [ -f "$file" ] && grep "^$plugin " "$file" > /dev/null; then
     sed -i.bak -e "s/^$plugin .*$/$plugin ${versions[*]}/" "$file"
     rm "$file".bak

lib/utils.sh

@@ -354,3 +354,12 @@ find_tool_versions() {
         search_path=$(dirname "$search_path")
     done
 }
+
+resolve_symlink() {
+    local symlink
+    symlink="$1"
+
+    # This seems to be the only cross-platform way to resolve symlink paths to
+    # the real file path
+    ls -l "$symlink" | sed -e "s|.*-> \(.*\)|\1|"
+}