As string is iterable, changed to isinstance check

test now works

.gitignore

@@ -15,3 +15,5 @@ nbproject
 /*egg-info
 /.tox
 /.vscode/
+.idea/
+.cache/

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "gitdb"]
-	url = https://github.com/gitpython-developers/gitdb.git
-	path = git/ext/gitdb
+[submodule "gitdb"]
+	url = https://github.com/gitpython-developers/gitdb.git
+	path = git/ext/gitdb

git/index/base.py

@@ -569,10 +569,8 @@ def _preprocess_add_items(self, items):
         """ Split the items into two lists of path strings and BaseEntries. """
         paths = []
         entries = []
-        # check if is iterable, else put in list
-        try:
-            test_item = iter(items)
-        except TypeError:
+        # if it is a string put in list
+        if isinstance(items, str):
             items = [items]
 
         for item in items:
@@ -806,10 +804,8 @@ def _items_to_rela_paths(self, items):
         """Returns a list of repo-relative paths from the given items which
         may be absolute or relative paths, entries or blobs"""
         paths = []
-        # check if is iterable, else put in list
-        try:
-            test_item = iter(items)
-        except TypeError:
+        # if string put in list
+        if isinstance(items, str):
             items = [items]
 
         for item in items:

git/test/test_index.py

@@ -775,9 +775,11 @@ def test_compare_write_tree(self, rw_repo):
 
     @with_rw_repo('HEAD', bare=False)
     def test_index_single_addremove(self, rw_repo):
-        path = osp.join('git', 'test', 'test_index.py')
-        self._assert_entries(rw_repo.index.add(path))
-        deleted_files = rw_repo.index.remove(path)
+        fp = osp.join(rw_repo.working_dir, 'testfile.txt')
+        with open(fp, 'w') as fs:
+            fs.write(u'content of testfile')
+        self._assert_entries(rw_repo.index.add(fp))
+        deleted_files = rw_repo.index.remove(fp)
         assert deleted_files
 
     def test_index_new(self):