local history: index out of bounds fixed

platform/lvcs-impl/src/com/intellij/history/core/Paths.java

@@ -44,7 +44,6 @@ public class Paths {
   }
 
   public static String appended(String path, String child) {
-    if (path.length() == 0) return child;
     path = appendParent(path);
     return path + child;
   }
@@ -82,6 +81,7 @@ public class Paths {
   }
 
   private static String appendParent(String parent) {
+    if (parent.isEmpty()) return parent;
     if (parent.charAt(parent.length() - 1) != DELIM) parent += DELIM;
     return parent;
   }

platform/lvcs-impl/testSrc/com/intellij/history/core/PathsTest.java

@@ -42,6 +42,8 @@ public class PathsTest extends LocalHistoryTestCase {
     assertEquals("c:/root/file", Paths.appended("c:/root", "file"));
     assertEquals("/foo", Paths.appended("/", "foo"));
     assertEquals("/foo/bar", Paths.appended("/foo", "bar"));
+
+    assertEquals("bar", Paths.appended("", "bar"));
   }
 
   @Test
@@ -79,6 +81,8 @@ public class PathsTest extends LocalHistoryTestCase {
     assertFalse(Paths.isParent("foo/bar", "foo/baz"));
     assertFalse(Paths.isParent("foo/bar", "foo/barr"));
     assertFalse(Paths.isParent("foo/bar", "foo/barr/baz"));
+
+    assertTrue(Paths.isParent("", "foo"));
   }
 
   @Test