Normalize commit messages on automerge (#151)

Remove HTML comments and unwanted leading and trailing whitespace
from the commit message.

Fixes #150

Author: zware

miss_islington/status_change.py

@@ -99,7 +99,7 @@ async def merge_pr(gh, pr, sha, is_automerge=False):
     async for commit in gh.getiter(f"/repos/python/cpython/pulls/{pr_number}/commits"):
         if commit["sha"] == sha:
             if is_automerge:
-                pr_commit_msg = pr["body"]
+                pr_commit_msg = util.normalize_message(pr["body"])
                 pr_title = f"{pr['title']} (GH-{pr_number})"
                 await gh.put(
                     f"/repos/python/cpython/pulls/{pr_number}/merge",

miss_islington/util.py

@@ -105,6 +105,19 @@ def normalize_title(title, body):
         return title[:-1] + body[1:].partition("\r\n")[0]
 
 
+def normalize_message(body):
+    """Normalize the message body to make it commit-worthy.
+
+    Mostly this just means removing HTML comments, but also removes unwanted
+    leading or trailing whitespace.
+
+    Returns the normalized body.
+    """
+    while "<!--" in body:
+        body = body[: body.index("<!--")] + body[body.index("-->") + 3 :]
+    return "\n\n" + body.strip()
+
+
 # Copied over from https://github.com/python/bedevere
 async def is_core_dev(gh, username):
     """Check if the user is a CPython core developer."""

tests/test_util.py

@@ -55,6 +55,17 @@ def test_title_normalization():
     assert util.normalize_title(title, body) == expected
 
 
+def test_message_normalization():
+    message = "<!-- This is an HTML comment -->And this is the part we want"
+    assert util.normalize_message(message) == "\n\nAnd this is the part we want"
+
+    message = "<!-- HTML comment -->Part we want<!-- HTML comment 2 -->"
+    assert util.normalize_message(message) == "\n\nPart we want"
+
+    message = "\r\nParts <!--comment--> we want\r\nincluded"
+    assert util.normalize_message(message) == "\n\nParts  we want\r\nincluded"
+
+
 async def test_get_gh_participants_different_creator_and_committer():
     gh = FakeGH(
         getitem={