Here is stacktrace:
2016-01-15 14:10:40.533 ERROR glance.common.wsgi [req-f3df3782-3990-4a9b-aa9b-5e095b396f1f e994214113a74668be2c1290fafa3422 06a11b992e264ba5bf67816edb283e61] Caught error: <class 'glance.common.exception.RPCError'> exception was raised in the last rpc call: Multiple rows were found for one()
2016-01-15 14:10:40.533 TRACE glance.common.wsgi Traceback (most recent call last):
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/common/wsgi.py", line 885, in __call__
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     request, **action_args)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/common/wsgi.py", line 919, in dispatch
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return method(*args, **kwargs)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/common/utils.py", line 423, in wrapped
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return func(self, req, *args, **kwargs)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/api/v2/image_tags.py", line 78, in delete
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     image_repo.save(image)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/domain/proxy.py", line 99, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = self.base.save(base_item, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/notifier.py", line 458, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     super(ImageRepoProxy, self).save(image, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/domain/proxy.py", line 99, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = self.base.save(base_item, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/api/policy.py", line 125, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return super(ImageRepoProxy, self).save(image, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/domain/proxy.py", line 99, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = self.base.save(base_item, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/quota/__init__.py", line 112, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return super(ImageRepoProxy, self).save(image, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/domain/proxy.py", line 99, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = self.base.save(base_item, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/location.py", line 65, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = super(ImageRepoProxy, self).save(image, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/domain/proxy.py", line 99, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     result = self.base.save(base_item, from_state=from_state)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/db/__init__.py", line 281, in save
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     image.tags)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/db/registry/api.py", line 52, in wrapper
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return func(client, *args, **kwargs)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/db/registry/api.py", line 217, in image_tag_set_all
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     client.image_tag_set_all(image_id=image_id, tags=tags)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/common/rpc.py", line 278, in method_proxy
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     return self.do_request(item, **kw)
2016-01-15 14:10:40.533 TRACE glance.common.wsgi   File "/opt/stack/glance/glance/common/rpc.py", line 260, in do_request
2016-01-15 14:10:40.533 TRACE glance.common.wsgi     raise exc_cls(error['val'])
2016-01-15 14:10:40.533 TRACE glance.common.wsgi RPCError: <class 'glance.common.exception.RPCError'> exception was raised in the last rpc call: Multiple rows were found for one()