test(prometheus): set the template's version line whatever it is, not only version: 1 (#5693)

Run 9095: with the Archives template at version 2, the library test's
"bad" copy no longer had a bad version, saved, and took the name the
real save then wanted.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_prometheus_template_library.py

@@ -8,6 +8,7 @@ import asyncio
 import io
 import json
 import os
+import re
 import time
 import uuid
 
@@ -59,6 +60,14 @@ def _prom(sub):
     return importlib.import_module(f"{loaded.__name__ if loaded else 'plugins.prometheus'}.{sub}")
 
 
+def _version(text: str, value: str) -> str:
+    """`text` with its top-level version: line set to `value`, whatever the
+    bundled template's own version is."""
+    changed, n = re.subn(r"(?m)^version:.*$", f"version: {value}", text, count=1)
+    assert n == 1
+    return changed
+
+
 def _text(page: str) -> str:
     return " ".join(page.split())
 
@@ -89,7 +98,7 @@ def test_an_admin_copies_edits_previews_exports_and_deletes_a_template(app):
 
         # A template with a problem isn't saved, and says where.
         bad = await admin.post("/plugins/prometheus/templates/new", headers=CSRF,
-                               form={"text": text.replace("version: 1", "version: one")})
+                               form={"text": _version(text, "one")})
         out["bad"] = (bad.status_code, "Not saved." in _text(await bad.get_data(as_text=True)))
         # The bundled template's name is taken.
         clash = await admin.post("/plugins/prometheus/templates/new", headers=CSRF,
@@ -109,7 +118,7 @@ def test_an_admin_copies_edits_previews_exports_and_deletes_a_template(app):
         page = _text(await (await admin.get(where)).get_data(as_text=True))
         out["editable"] = f'action="/plugins/prometheus/templates/{key}/edit"' in page and "Your own" in page
 
-        renamed = library.renamed(text, f"{mine} v2").replace("version: 1", "version: 2")
+        renamed = _version(library.renamed(text, f"{mine} v2"), "9")
         edit = await admin.post(f"/plugins/prometheus/templates/{key}/edit", headers=CSRF, form={"text": renamed})
         out["edited"] = edit.status_code