build: trigger_action.py is more helpful

Makefile

@@ -192,7 +192,7 @@ cheats:					## Create some useful snippets for releasing.
 	python igor.py cheats | tee cheats.txt
 
 relbranch:				#: Create the branch for releasing (see howto.txt).
-	git switch -c nedbat/release-$$(date +%Y%m%d)
+	git switch -c nedbat/release-$$(date +%Y%m%d-%H%M%S)
 
 relcommit1:				#: Commit the first release changes (see howto.txt).
 	git commit -am "docs: prep for $$(python setup.py --version)"
@@ -206,9 +206,11 @@ kit:					## Make the source distribution.
 
 pypi_upload:				## Upload the built distributions to PyPI.
 	python ci/trigger_action.py $(REPO_OWNER) publish-pypi
+	@echo "Use that^ URL to approve the upload"
 
 test_upload:				## Upload the distributions to PyPI's testing server.
 	python ci/trigger_action.py $(REPO_OWNER) publish-testpypi
+	@echo "Use that^ URL to approve the upload"
 
 kit_local:
 	# pip.conf looks like this:

ci/trigger_action.py

@@ -4,11 +4,10 @@
 """Trigger a repository_dispatch GitHub action."""
 
 import sys
+import time
 
 from session import get_session
 
-repo_owner, event_type = sys.argv[1:]
-
 # The GitHub URL makes no mention of which workflow to use. It's found based on
 # the event_type, which matches the types in the workflow:
 #
@@ -18,12 +17,39 @@
 #         - build-kits
 #
 
-url = f"https://api.github.com/repos/{repo_owner}/dispatches"
-data = {"event_type": event_type}
 
-resp = get_session().post(url, json=data)
-if resp.status_code // 100 == 2:
-    print("Success")
-else:
-    print(f"Status: {resp.status_code}")
-    print(resp.text)
+def latest_action_run(repo_owner, event):
+    """
+    Get the newest action run for a certain kind of event.
+    """
+    resp = get_session().get(
+        f"https://api.github.com/repos/{repo_owner}/actions/runs?event={event}"
+    )
+    resp.raise_for_status()
+    return resp.json()["workflow_runs"][0]
+
+
+def dispatch_action(repo_owner, event_type):
+    """
+    Trigger an action with a particular dispatch event_type.
+    Wait until it starts, and print the URL to it.
+    """
+    latest_id = latest_action_run(repo_owner, "repository_dispatch")["id"]
+
+    url = f"https://api.github.com/repos/{repo_owner}/dispatches"
+    data = {"event_type": event_type}
+
+    resp = get_session().post(url, json=data)
+    resp.raise_for_status()
+    print(f"Success: {resp.status_code}")
+    while True:
+        run = latest_action_run(repo_owner, "repository_dispatch")
+        if run["id"] != latest_id:
+            break
+        print(".", end=" ", flush=True)
+        time.sleep(0.5)
+    print(run["html_url"])
+
+
+if __name__ == "__main__":
+    dispatch_action(*sys.argv[1:])