abrt version: 1.1.14
architecture: x86_64
cmdline: /usr/bin/python /usr/bin/bootchart -o .
comment: None of the three worked, hit this as I tried to see if bug #666149 happends when the output directory is something writeable.
component: bootchart
executable: /usr/bin/bootchart
kernel: 2.6.37-0.rc7.git0.2.fc15.x86_64
package: bootchart-0.12.4-3.1.git20101122.fc15
reason: main.py:101:_get_filename:TypeError: cannot concatenate 'str' and 'NoneType' objects
release: Fedora release 15 (Rawhide)
time: 1293608784
uid: 500

backtrace
-----
main.py:101:_get_filename:TypeError: cannot concatenate 'str' and 'NoneType' objects

Traceback (most recent call last):
  File "/usr/bin/bootchart", line 23, in <module>
    sys.exit(main())
  File "/usr/lib/python2.7/site-packages/pybootchartgui/main.py", line 142, in main
    filename = _get_filename(args, options)
  File "/usr/lib/python2.7/site-packages/pybootchartgui/main.py", line 101, in _get_filename
    return os.path.join (dname, fname + "." + options.format)
TypeError: cannot concatenate 'str' and 'NoneType' objects

Local variables in innermost frame:
dname: '.'
path: '/var/log/bootchart.tgz'
options: <Values at 0x1f14fc8: {'profile': False, 'verbose': False, 'format': None, 'show_all': False, 'annotate_file': None, 'quiet': False, 'annotate': None, 'show_pid': False, 'crop_after': None, 'boottime': False, 'prune': True, 'output': '.', 'veryquiet': False, 'interactive': False}>
fname: '/var/log/bootchart'
paths: ['/var/log/bootchart.tgz']

How to reproduce
-----
1. bootchart -o .
2. bootchart -o ~
3. bootchart --output=/home/xake