Submodule.add() can now handle absolute module paths in agreement to the doc string.

Previously, it would say it can handle absolute module paths, but didn't
actually do so.
A test-case was improved to check for this case.

Fixes gitpython-developers#161

Author: Byron

git/objects/submodule/base.py

@@ -238,6 +238,17 @@ def add(cls, repo, name, path, url=None, branch=None, no_checkout=False):
             path = path[:-1]
         # END handle trailing slash
 
+        if os.path.isabs(path):
+            working_tree_linux = to_native_path_linux(repo.working_tree_dir)
+            if not path.startswith(working_tree_linux):
+                raise ValueError("Submodule checkout path '%s' needs to be within the parents repository at '%s'"
+                                 % (working_tree_linux, path))
+            path = path[len(working_tree_linux) + 1:]
+            if not path:
+                raise ValueError("Absolute submodule path '%s' didn't yield a valid relative path" % path)
+            # end verify converted relative path makes sense
+        # end convert to a relative path
+
         # assure we never put backslashes into the url, as some operating systems
         # like it ...
         if url is not None:

git/test/test_submodule.py

@@ -586,6 +586,14 @@ def test_root_module(self, rwrepo):
     @with_rw_repo(k_no_subm_tag, bare=False)
     def test_first_submodule(self, rwrepo):
         assert len(list(rwrepo.iter_submodules())) == 0
-        sm = rwrepo.create_submodule('first', 'submodules/first', rwrepo.git_dir, no_checkout=True)
-        assert sm.exists() and sm.module_exists()
-        rwrepo.index.commit("Added submodule")
+
+        for sm_name, sm_path in (('first', 'submodules/first'),
+                                 ('second', os.path.join(rwrepo.working_tree_dir, 'submodules/second'))):
+            sm = rwrepo.create_submodule(sm_name, sm_path, rwrepo.git_dir, no_checkout=True)
+            assert sm.exists() and sm.module_exists()
+            rwrepo.index.commit("Added submodule " + sm_name)
+        # end for each submodule path to add
+
+        self.failUnlessRaises(ValueError, rwrepo.create_submodule, 'fail', os.path.expanduser('~'))
+        self.failUnlessRaises(ValueError, rwrepo.create_submodule, 'fail-too',
+                              rwrepo.working_tree_dir + os.path.sep)