FileSystem: Fix FS path comparison, write from stream to new path only

* Always resolve fsBasePath to absolute path for later comparison
* Always transform stream into buffer if write path equals source path

lib/adapters/FileSystem.js

@@ -31,7 +31,7 @@ class FileSystem extends AbstractAdapter {
 	 */
 	constructor({virBasePath, project, fsBasePath, excludes}) {
 		super({virBasePath, project, excludes});
-		this._fsBasePath = fsBasePath;
+		this._fsBasePath = path.resolve(fsBasePath);
 	}
 
 	/**
@@ -240,7 +240,7 @@ class FileSystem extends AbstractAdapter {
 		return new Promise((resolve, reject) => {
 			let contentStream;
 
-			if (drain || readOnly) {
+			if ((drain || readOnly) && resourceSource.fsPath !== fsPath) {
 				// Stream will be drained
 				contentStream = resource.getStream();