fix git command for dep which points to a tag

dbt/clients/git.py

@@ -1,5 +1,6 @@
 from dbt.clients.system import run_cmd
 from dbt.logger import GLOBAL_LOGGER as logger
+import dbt.exceptions
 
 
 def clone(repo, cwd, dirname=None):
@@ -11,17 +12,36 @@ def clone(repo, cwd, dirname=None):
     return run_cmd(cwd, clone_cmd)
 
 
-def checkout(cwd, branch=None):
+def list_tags(cwd):
+    out, err = run_cmd(cwd, ['git', 'tag', '--list'])
+    tags = set(out.decode('utf-8').strip().split("\n"))
+    return tags
+
+
+def checkout(cwd, repo, branch=None):
     if branch is None:
         branch = 'master'
 
-    remote_branch = 'origin/{}'.format(branch)
-
     logger.info('  Checking out branch {}.'.format(branch))
 
     run_cmd(cwd, ['git', 'remote', 'set-branches', 'origin', branch])
-    run_cmd(cwd, ['git', 'fetch', '--depth', '1', 'origin', branch])
-    run_cmd(cwd, ['git', 'reset', '--hard', remote_branch])
+    run_cmd(cwd, ['git', 'fetch', '--tags', '--depth', '1', 'origin', branch])
+
+    tags = list_tags(cwd)
+
+    # Prefer tags to branches if one exists
+    if branch in tags:
+        spec = 'tags/{}'.format(branch)
+    else:
+        spec = 'origin/{}'.format(branch)
+
+    out, err = run_cmd(cwd, ['git', 'reset', '--hard', spec])
+    stderr = err.decode('utf-8').strip()
+
+    if stderr.startswith('fatal:'):
+        dbt.exceptions.bad_package_spec(repo, branch, stderr)
+    else:
+        return out, err
 
 
 def get_current_sha(cwd):

dbt/clients/system.py

@@ -109,4 +109,9 @@ def run_cmd(cwd, cmd):
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE)
 
-    return proc.communicate()
+    out, err = proc.communicate()
+
+    logger.debug('STDOUT: "{}"'.format(out))
+    logger.debug('STDERR: "{}"'.format(err))
+
+    return out, err

dbt/exceptions.py

@@ -124,3 +124,9 @@ def missing_sql_where(model):
         model,
         "Model '{}' is materialized as 'incremental', but does not have a "
         "sql_where defined in its config.".format(model.get('unique_id')))
+
+
+def bad_package_spec(repo, spec, error_message):
+    raise RuntimeException(
+        "Error checking out spec='{}' for repo {}\n{}".format(
+            spec, repo, error_message))

dbt/task/deps.py

@@ -40,7 +40,7 @@ def __pull_repo(self, repo, branch=None):
 
         dependency_path = os.path.join(modules_path, folder)
         start_sha = dbt.clients.git.get_current_sha(dependency_path)
-        dbt.clients.git.checkout(dependency_path, branch)
+        dbt.clients.git.checkout(dependency_path, repo, branch)
         end_sha = dbt.clients.git.get_current_sha(dependency_path)
 
         if exists:

test/integration/023_exit_codes_test/test_exit_codes.py

@@ -167,9 +167,12 @@ def project_config(self):
 
     @attr(type='postgres')
     def test_deps(self):
-        _, success = self.run_dbt_and_check(['deps'])
-        # TODO : https://github.com/fishtown-analytics/dbt/issues/463
-        # self.assertFalse(success)
+        # this should fail
+        try:
+            _, success = self.run_dbt_and_check(['deps'])
+            self.assertTrue(False)
+        except RuntimeError as e:
+            pass
 
 class TestExitCodesSeed(DBTIntegrationTest):
     @property