conf: detect and handle blank usernames

Fix situation where osc has added a blank username to the keyring and
update the config parse script to do the right thing and not allow blank
usernames.

I was in a very confusing situation where my keyring ended up with two
entries:

- @api.suse.de
- philipsb@api.suse.de

And I was getting 401s because of it.

Signed-off-by: Brandon Philips <bphilips@suse.de>

osc/conf.py

@@ -769,6 +769,13 @@ def get_config(override_conffile = None,
             except gnomekeyring.NoMatchError:
                 # Fallback to file based auth.
                 pass
+
+        if not user is None and len(user) == 0:
+            user = None
+            print >>sys.stderr, "Warning: blank user in the keyring for the "\
+                                "api url %s.\nRun seahorse to fix the "\
+                                "entry.\n" % (url)
+
         # Read credentials from config
         if user is None:
             #FIXME: this could actually be the ideal spot to take defaults
@@ -776,6 +783,10 @@ def get_config(override_conffile = None,
             user         = cp.get(url, 'user', raw=True) # need to set raw to prevent '%' expansion
             password     = cp.get(url, 'pass', raw=True) # especially on password!
             passwordx    = cp.get(url, 'passx', raw=True) # especially on password!
+            if user is None or len(user) == 0:
+                raise oscerr.ConfigError("user is blank for %s" % apiurl,
+                                            config['conffile'])
+
             if password is None or password == 'your_password':
                 try:
                     password = passwordx.decode('base64').decode('bz2')