fix: report SAML issue as fatal

Currently this is catched as AuthentificationFailure making Mergify
retrying for ever. This change mark the SAML message as fatal. So
the error message coming from Github is reported on the PullRequest.

Related #1145
Fixes MERGIFY-ENGINE-1MG

mergify_engine/branch_updater.py

@@ -15,6 +15,7 @@
 # under the License.
 
 
+import collections
 import subprocess
 import uuid
 
@@ -44,20 +45,23 @@ class AuthentificationFailure(Exception):
     pass
 
 
-GIT_MESSAGE_TO_EXCEPTION = {
-    b"Invalid username or password": AuthentificationFailure,
-    b"Repository not found": AuthentificationFailure,
-    b"The requested URL returned error: 403": AuthentificationFailure,
-    b"Patch failed at": BranchUpdateFailure,
-    b"remote contains work that you do": BranchUpdateNeedRetry,
-    b"remote end hung up unexpectedly": BranchUpdateNeedRetry,
-    b"cannot lock ref 'refs/heads/": BranchUpdateNeedRetry,
-    b"Could not resolve host": BranchUpdateNeedRetry,
-    b"Operation timed out": BranchUpdateNeedRetry,
-    b"No such device or address": BranchUpdateNeedRetry,
-    b"Protected branch update failed": BranchUpdateFailure,
-    b"Couldn't find remote ref": BranchUpdateFailure,
-}
+GIT_MESSAGE_TO_EXCEPTION = collections.OrderedDict(
+    [
+        (b"organization has enabled or enforced SAML SSO.", BranchUpdateFailure),
+        (b"Invalid username or password", AuthentificationFailure),
+        (b"Repository not found", AuthentificationFailure),
+        (b"The requested URL returned error, 403", AuthentificationFailure),
+        (b"Patch failed at", BranchUpdateFailure),
+        (b"remote contains work that you do", BranchUpdateNeedRetry),
+        (b"remote end hung up unexpectedly", BranchUpdateNeedRetry),
+        (b"cannot lock ref 'refs/heads/", BranchUpdateNeedRetry),
+        (b"Could not resolve host", BranchUpdateNeedRetry),
+        (b"Operation timed out", BranchUpdateNeedRetry),
+        (b"No such device or address", BranchUpdateNeedRetry),
+        (b"Protected branch update failed", BranchUpdateFailure),
+        (b"Couldn't find remote ref", BranchUpdateFailure),
+    ]
+)
 
 GIT_MESSAGE_TO_UNSHALLOW = set([b"shallow update not allowed", b"unrelated histories"])