Allow specifying which projects to update

This allows to specify which projects to update instead of running on
all of them.
The project should be provided in form of namespace/name, for example:
``-p rpms/koji rpms/guake``.

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

distgit_bugzilla_sync/script.py

@@ -484,10 +484,14 @@ class DistgitBugzillaSync:
         parser.add_argument('--add-email-overrides-file', metavar='EMAIL_OVERRIDES_FILE',
                             dest='addl_email_overrides_files', action='append',
                             help="File(s) from which to read additional email overrides")
+        parser.add_argument(
+            '-p', '--project', dest='projects', nargs='+',
+            help='Update one or more projects (provided as namespace/name), '
+            'in all of its products')
 
         self.args = parser.parse_args()
 
-    def get_pagure_project(self):
+    def get_pagure_project(self, project_list=None):
         """ Builds a large list of all the projects on pagure.
         Each item in that list is a dict containing:
         - the namespace of the project
@@ -511,14 +515,17 @@ class DistgitBugzillaSync:
 
         # Combine and collapse those two into a single list:
         self.pagure_projects = []
+        if project_list:
+            project_list = set(tuple(p.split("/", 1)) for p in project_list)
         for namespace, entries in pagure_namespace_to_poc.items():
             for name, poc in entries.items():
-                self.pagure_projects.append(dict(
-                    namespace=namespace,
-                    name=name,
-                    poc=poc,
-                    watchers=pagure_namespace_to_cc[namespace][name],
-                ))
+                if not project_list or (namespace, name) in project_list:
+                    self.pagure_projects.append(dict(
+                        namespace=namespace,
+                        name=name,
+                        poc=poc,
+                        watchers=pagure_namespace_to_cc[namespace][name],
+                    ))
 
     def add_branches_product_and_summary(self):
         """ For each project retrieved this method adds branches, products
@@ -645,12 +652,14 @@ class DistgitBugzillaSync:
             print("Building a cache of the rpm packages' summary")
         self.rpm_summary = package_summary.get_package_summary()
 
-        self.get_pagure_project()
+        self.get_pagure_project(self.args.projects)
         self.add_branches_product_and_summary()
 
         if self.env["verbose"]:
             print(f"{len(self.pagure_projects)} projects to consider")
 
+        if not self.pagure_projects:
+            return
         if self.env["verbose"]:
             times["data structure end"] = time.time()
             delta = times["data structure end"] - times["start"]