Removed sqlalchemy from install_requires.

showing useful error message if the database result backend
is used and it's not installed.

celery/backends/database.py

@@ -1,12 +1,19 @@
 from datetime import datetime
 
-
 from celery import conf
 from celery.backends.base import BaseDictBackend
 from celery.db.models import Task, TaskSet
 from celery.db.session import ResultSession
 from celery.exceptions import ImproperlyConfigured
 
+try:
+    import sqlalchemy as _
+except ImportError:
+    raise ImproperlyConfigured(
+        "The database result backend requires SQLAlchemy to be installed."
+        "See http://pypi.python.org/pypi/SQLAlchemy")
+
+
 
 class DatabaseBackend(BaseDictBackend):
     """The database result backend."""

setup.py

@@ -36,7 +36,6 @@ except ImportError:
 
 install_requires.extend([
     "python-dateutil",
-    "sqlalchemy",
     "anyjson",
     "carrot>=0.10.5",
     "pyparsing",
@@ -54,7 +53,7 @@ else:
     long_description = "See http://pypi.python.org/pypi/celery"
 
 setup(
-    name='celery',
+    name="celery",
     version=distmeta.__version__,
     description=distmeta.__doc__,
     author=distmeta.__author__,