Rework module updating

1 files changed, 16 insertions, 3 deletions

diff --git a/devbot/build.py b/devbot/build.py
index 7b2e9b4..9c616aa 100644
--- a/devbot/build.py
+++ b/devbot/build.py
@@ -9,6 +9,7 @@ from devbot import command
 from devbot import config
 from devbot import environ
 from devbot import state
+from devbot import utils
 
 def build_one(module_name):
     environ.setup()
@@ -85,6 +86,11 @@ def _unlink_libtool_files():
 
     os.path.walk(config.lib_dir, func, None)
 
+def _is_detached_head():
+    return subprocess.call(["git", "symbolic-ref", "-q", "HEAD"],
+                           stdout=utils.devnull,
+                           stderr=subprocess.STDOUT) != 0
+
 def _pull_git_module(module):
     module_dir = module.get_source_dir()
 
@@ -92,14 +98,21 @@ def _pull_git_module(module):
         os.chdir(module_dir)
 
         command.run(["git", "remote", "set-url", "origin", module.repo])
-        command.run(["git", "remote", "update", "origin"], retry=10)
+
+        if _is_detached_head():
+            command.run(["git", "remote", "update", "origin"], retry=10)
+            command.run(["git", "checkout", module.branch])
+        else:
+            command.run(["git", "checkout", module.branch])
+            command.run(["git", "pull"], retry=10)
     else:
         os.chdir(config.get_source_dir())
+
         command.run(["git", "clone", "--progress", module.repo, module.name],
                     retry=10)
-        os.chdir(module_dir)
 
-    command.run(["git", "checkout", module.branch])
+        os.chdir(module_dir)
+        command.run(["git", "checkout", module.branch])
 
 def _pull_module(module):
     print "\n=== Pulling %s ===\n" % module.name