address review: reject key extraction when GPG verification fails

The release verification script was emitting "Warning: No email address
found in GPG verification output" and then falling back to "RSA/EDDSA
key verified, but Email not available for verification" — so the email
portion of the KEYS check was effectively never exercised.

Two underlying issues:

1. If the signer's public key isn't in the local keyring, `gpg --verify`
   exits with "Can't check signature: No public key" and prints only
   the key ID — no signature is actually verified. The script silently
   accepted that state.
2. Even when verification succeeds, modern gpg output puts the email
   on the `Good signature from "Name <email>"` line. The script only
   matched `issuer "..."`, which isn't always present.

Fix:

- Auto-import the Apache Superset KEYS file if gpg reports no public
  key, then re-run verification so the signature is genuinely checked.
- Match email from `Good signature from`, `aka`, and `issuer` lines in
  that order of reliability.
- Print the email that was found and, when no public key is available
  even after the import attempt, show the manual import command as a
  hint.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

RELEASING/verify_release.py

@@ -56,8 +56,33 @@ def verify_sha512(filename: str) -> str:
 # Part 2: Verify RSA key - this is the same as running `gpg --verify {release}.asc {release}` and comparing the RSA key and email address against the KEYS file  # noqa: E501
 
 
+KEYS_URL = "https://downloads.apache.org/superset/KEYS"
+
+
+def ensure_keys_imported() -> None:
+    """Import the Apache Superset KEYS file into the local GPG keyring.
+
+    Without this, `gpg --verify` returns "No public key" and the signature
+    cannot actually be verified — only the key ID in the signature metadata
+    is visible.
+    """
+    try:
+        keys = requests.get(KEYS_URL, timeout=30)
+    except requests.RequestException as exc:
+        print(f"Warning: could not fetch KEYS file for import: {exc}")
+        return
+    if keys.status_code != 200:
+        print(f"Warning: could not fetch KEYS file (HTTP {keys.status_code})")
+        return
+    subprocess.run(  # noqa: S603
+        ["gpg", "--import"],  # noqa: S607
+        input=keys.content,
+        capture_output=True,
+    )
+
+
 def get_gpg_info(filename: str) -> tuple[Optional[str], Optional[str]]:
-    """Run the GPG verify command and extract RSA key and email address."""
+    """Run the GPG verify command and extract RSA/EDDSA key and email address."""
     asc_filename = filename + ".asc"
     result = subprocess.run(  # noqa: S603
         ["gpg", "--verify", asc_filename, filename],  # noqa: S607
@@ -65,23 +90,55 @@ def get_gpg_info(filename: str) -> tuple[Optional[str], Optional[str]]:
     )
     output = result.stderr.decode()
 
+    # If no public key was available, import KEYS and retry so that
+    # `Good signature from "Name <email>"` appears in the output.
+    if "No public key" in output:
+        ensure_keys_imported()
+        result = subprocess.run(  # noqa: S603
+            ["gpg", "--verify", asc_filename, filename],  # noqa: S607
+            capture_output=True,  # noqa: S607
+        )
+        output = result.stderr.decode()
+
+    # If the signature was not actually verified, do not trust the key ID or
+    # email pulled from signature metadata — returning them would let the
+    # caller report the release as "verified" when GPG never validated it.
+    if result.returncode != 0 or "Good signature" not in output:
+        print("Warning: GPG could not verify the signature.")
+        if "No public key" in output:
+            print(
+                "Hint: public key is not in your keyring. Import it with:\n"
+                f"  curl -s {KEYS_URL} | gpg --import"
+            )
+        return None, None
+
     rsa_key = re.search(r"RSA key ([0-9A-F]+)", output)
     eddsa_key = re.search(r"EDDSA key ([0-9A-F]+)", output)
-    email = re.search(r'issuer "([^"]+)"', output)
+
+    # Try multiple patterns — `Good signature from` is the most reliable
+    # source of the email; `issuer` is a fallback for older gpg output.
+    email_patterns = (
+        r'Good signature from ".*?<([^>]+)>"',
+        r'aka ".*?<([^>]+)>"',
+        r'issuer "([^"]+)"',
+    )
+    email_result: Optional[str] = None
+    for pattern in email_patterns:
+        match = re.search(pattern, output)
+        if match:
+            email_result = match.group(1)
+            break
 
     rsa_key_result = rsa_key.group(1) if rsa_key else None
     eddsa_key_result = eddsa_key.group(1) if eddsa_key else None
-    email_result = email.group(1) if email else None
-
     key_result = rsa_key_result or eddsa_key_result
 
-    # Debugging:
     if key_result:
         print("RSA or EDDSA Key found")
     else:
         print("Warning: No RSA or EDDSA key found in GPG verification output.")
     if email_result:
-        print("email found")
+        print(f"Email found: {email_result}")
     else:
         print("Warning: No email address found in GPG verification output.")