Python 2.7 为什么buildbot抛出ImportError：无法导入名称异常？

我目前正在努力理解buildbot，并正在学习本课程的第一部分。但是我被困在我应该创造大师的地方。我试图通过使用网站修复错误，但仍然给我错误

Traceback (most recent call last):
File "./bin/buildbot", line 5, in <module>
pkg_resources.run_script('buildbot==0.8.7p1', 'buildbot')
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg/pkg_resources.py", line 489, in run_script
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg/pkg_resources.py", line 1207, in run_script
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/buildbot-0.8.7p1-py2.7.egg/EGG-INFO/scripts/buildbot", line 4, in <module>
runner.run()
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/buildbot-0.8.7p1-py2.7.egg/buildbot/scripts/runner.py", line 696, in run
subcommandFunction = reflect.namedObject(subconfig.subcommandFunction)
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/Twisted-13.0.0-py2.7- linux-x86_64.egg/twisted/python/_reflectpy3.py", line 151, in namedObject
module = namedModule('.'.join(classSplit[:-1]))
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/Twisted-13.0.0-py2.7-linux-x86_64.egg/twisted/python/_reflectpy3.py", line 137, in namedModule
topLevel = __import__(name)
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/buildbot-0.8.7p1-py2.7.egg/buildbot/scripts/create_master.py", line 23, in <module>
from buildbot.db import connector
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/buildbot-0.8.7p1-py2.7.egg/buildbot/db/connector.py", line 22, in <module>
from buildbot.db import pool, model, changes, schedulers, sourcestamps, sourcestampsets
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/buildbot-0.8.7p1-py2.7.egg/buildbot/db/model.py", line 18, in <module>
import migrate.versioning.schema
File "/home/hari/tmp/buildbot/sandbox/lib/python2.7/site-packages/sqlalchemy_migrate-0.7.2-py2.7.egg/migrate/versioning/schema.py", line 10, in <module>
from sqlalchemy import exceptions as sa_exceptions
ImportError: cannot import name exceptions

回溯（最近一次呼叫最后一次）：
文件“/bin/buildbot”，第5行，在
pkg_资源。运行_脚本（'buildbot==0.8.7p1'，'buildbot'）
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/setuptools-0.6c11-py2.7.egg/pkg_resources.py”，第489行，在run_脚本中
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/setuptools-0.6c11-py2.7.egg/pkg_resources.py”，第1207行，运行_脚本
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/buildbot-0.8.7p1-py2.7.egg/egg-INFO/scripts/buildbot”，第4行，在
runner.run（）
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/buildbot-0.8.7p1-py2.7.egg/buildbot/scripts/runner.py”，第696行，正在运行
SUBSCANDFUNCTION=reflect.namedObject（SUBSCANDFIG.SUBSCANDFUNCTION）
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/Twisted-13.0.0-py2.7-linux-x86_64.egg/Twisted/python/_reflectpy3.py”，第151行，在namedObject中
module=namedModule（'.'.join（classSplit[：-1]））
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/Twisted-13.0.0-py2.7-linux-x86_64.egg/Twisted/python/_reflectpy3.py”，第137行，在namedModule中
topLevel=\uuuuu导入\uuuuu（名称）
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/buildbot-0.8.7p1-py2.7.egg/buildbot/scripts/create_master.py”，第23行
从buildbot.db导入连接器
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/buildbot-0.8.7p1-py2.7.egg/buildbot/db/connector.py”，第22行
从buildbot.db导入池、模型、更改、调度程序、sourcestamps、SourceStampSet
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/buildbot-0.8.7p1-py2.7.egg/buildbot/db/model.py”，第18行，在
导入migrate.versioning.schema
文件“/home/hari/tmp/buildbot/sandbox/lib/python2.7/site packages/sqlalchemy\u migrate-0.7.2-py2.7.egg/migrate/versioning/schema.py”，第10行
从sqlalchemy将异常导入为sa_异常
ImportError:无法导入名称异常

转到

 sandbox/lib/python2.7/site-packages/sqlalchemy_migrate-0.*/migrate/versioning/schema.py at line 10

将异常更改为exc，使其看起来像

 from sqlalchemy import exc as sa_exceptions 

发生此错误。您可以通过安装早期版本来解决此问题：

$ pip uninstall sqlalchemy
$ pip install 'sqlalchemy <= 0.7.10'

$pip卸载sqlalchemy
$pip install'sqlalchemy是完整的回溯吗？安装不同版本的
sqlalchemy