Simplify PackageManager.getPackagePath

All callers ended up appending to the returned path,
so just do it in getPackagePath and save ourself some trouble.

source/dub/packagemanager.d

@@ -428,9 +428,6 @@ class PackageManager {
 
 		string gitReference = repo.ref_.chompPrefix("~");
 		NativePath destination = this.getPackagePath(PlacementLocation.user, name, repo.ref_);
-		// For libraries leaking their import path
-		destination ~= name;
-		destination.endsWithSlash = true;
 
 		foreach (p; getPackageIterator(name)) {
 			if (p.path == destination) {
@@ -724,8 +721,6 @@ class PackageManager {
 	{
 		NativePath dstpath = this.getPackagePath(dest, name, vers.toString());
 		ensureDirectory(dstpath);
-		// For libraries leaking their import path
-		dstpath = dstpath ~ name;
 
 		// possibly wait for other dub instance
 		import core.time : seconds;
@@ -1440,7 +1435,7 @@ package struct Location {
 
 		string versStr = vers.toString();
 		const lookupName = getBasePackageName(name);
-		const path = this.getPackagePath(lookupName, versStr) ~ (lookupName ~ "/");
+		const path = this.getPackagePath(lookupName, versStr);
 		if (!path.existsDirectory())
 			return null;
 
@@ -1461,13 +1456,12 @@ package struct Location {
 	 * which expects their containing folder to have an exact name and use
 	 * `importPath "../"`.
 	 *
-	 * Hence the final format should be `$BASE/$NAME-$VERSION/$NAME`,
-	 * but this function returns `$BASE/$NAME-$VERSION/`
+	 * Hence the final format returned is `$BASE/$NAME/$VERSION/$NAME`,
 	 * `$BASE` is `this.packagePath`.
 	 */
 	NativePath getPackagePath (string name, string vers)
 	{
-		NativePath result = this.packagePath ~ name ~ vers;
+		NativePath result = this.packagePath ~ name ~ vers ~ name;
 		result.endsWithSlash = true;
 		return result;
 	}

source/dub/test/base.d

@@ -335,8 +335,6 @@ package class TestPackageManager : PackageManager
 
 		string gitReference = repo.ref_.chompPrefix("~");
 		NativePath destination = this.getPackagePath(PlacementLocation.user, name, repo.ref_);
-		destination ~= name;
-		destination.endsWithSlash = true;
 
 		foreach (p; getPackageIterator(name))
 			if (p.path == destination)