lorax: Add option to exclude packages

Sometimes the repos you are using have broken deps. Now you
can exclude packages with -e or --excludepkgs

src/sbin/lorax

@@ -67,6 +67,9 @@ def main(args):
             help="config file", metavar="STRING")
     optional.add_option("--proxy", default=None,
             help="repo proxy url:port", metavar="STRING")
+    optional.add_option("-e", "--excludepkgs", default=[],
+            action="append", metavar="STRING",
+            help="package glob to exclude (may be listed multiple times)")
 
     # add the option groups to the parser
     parser.add_option_group(required)
@@ -106,7 +109,7 @@ def main(args):
     os.mkdir(yumtempdir)
 
     yb = get_yum_base_object(installtree, opts.source, opts.mirrorlist,
-                             yumtempdir, opts.proxy)
+                             yumtempdir, opts.proxy, opts.excludepkgs)
 
     if yb is None:
         print("error: unable to create the yumbase object", file=sys.stderr)
@@ -122,7 +125,7 @@ def main(args):
 
 
 def get_yum_base_object(installroot, repositories, mirrorlists=[],
-                        tempdir="/tmp", proxy=None):
+                        tempdir="/tmp", proxy=None, excludepkgs=[]):
 
     def sanitize_repo(repo):
         if repo.startswith("/"):
@@ -160,6 +163,9 @@ def get_yum_base_object(installroot, repositories, mirrorlists=[],
     if proxy:
         data["proxy"] = proxy
 
+    if excludepkgs:
+        data["exclude"] = " ".join(excludepkgs)
+
     c.add_section(section)
     map(lambda (key, value): c.set(section, key, value), data.items())