Tools: check_branch_conventions.py: sanity check author emails on commits

Tools/scripts/check_branch_conventions.py

@@ -129,6 +129,23 @@ class CheckBranchConventions(build_script_base.BuildScriptBase):
             print(f"{PASS} All commit subject lines within {MAX_SUBJECT_LEN} characters.")
         return ok
 
+    def check_author_emails(self) -> bool:
+        emails = self.run_git(
+            ["log", f"{self.base_branch}..HEAD", "--format=%ae"],
+            show_output=False,
+        ).strip()
+        bad = []
+        for email in emails.splitlines():
+            if "example.com" in email:
+                bad.append(email)
+        if bad:
+            print(f"{FAIL} Author email(s) with example.com are not allowed:")
+            for email in bad:
+                print(f"         {email}")
+            return False
+        print(f"{PASS} No unacceptable author emails.")
+        return True
+
     def check_markdown(self) -> bool:
         changed_md = self.run_git(
             ["diff", "--name-only", "--diff-filter=AM",
@@ -170,6 +187,7 @@ class CheckBranchConventions(build_script_base.BuildScriptBase):
             self.check_fixup_commits(commits),
             self.check_commit_messages(commits),
             self.check_commit_lengths(commits),
+            self.check_author_emails(),
             self.check_markdown(),
         ]