index: fail if user sets mirrors:isPrimary wrong

Really, this is not meant to be set by the user in the config.  But if they
add something harmless that'll be ignored anyway, it seems that throwing an
error is too much.  So only throw the error if it is set wrongly.

fdroidserver/index.py

@@ -1516,6 +1516,7 @@ def add_mirrors_to_repodict(repo_section, repodict):
     repodict['mirrors'] = []
     canonical_url = repodict['address']
     found_primary = False
+    errors = 0
     for mirror in mirrors:
         if canonical_url == mirror['url']:
             found_primary = True
@@ -1524,9 +1525,19 @@ def add_mirrors_to_repodict(repo_section, repodict):
             for k in sorted(mirror.keys()):
                 sortedmirror[k] = mirror[k]
             repodict['mirrors'].insert(0, sortedmirror)
+        elif mirror.get('isPrimary'):
+            errors += 1
+            logging.error(
+                _('Mirror config for {url} contains "isPrimary" key!').format(
+                    url=mirror['url']
+                )
+            )
         else:
             repodict['mirrors'].append(mirror)
 
+    if errors:
+        raise FDroidException(_('"isPrimary" key should not be added to mirrors!'))
+
     if repodict['mirrors'] and not found_primary:
         repodict['mirrors'].insert(0, {'isPrimary': True, 'url': repodict['address']})
 

tests/test_index.py

@@ -814,6 +814,19 @@ class IndexTest(unittest.TestCase):
         with self.assertRaises(fdroidserver.exception.FDroidException):
             index.add_mirrors_to_repodict('repo', repodict)
 
+    def test_erroneous_isPrimary_in_mirrors_config(self):
+        """There can be only one primary mirror aka canonical URL"""
+        common.config = {
+            'repo_url': 'http://one/fdroid',
+            'mirrors': [
+                {'url': 'http://one/fdroid', 'countryCode': 'SA'},
+                {'url': 'http://two/fdroid', 'isPrimary': True},
+            ],
+        }
+        repodict = {'address': common.config['repo_url']}
+        with self.assertRaises(fdroidserver.exception.FDroidException):
+            index.add_mirrors_to_repodict('repo', repodict)
+
 
 class AltstoreIndexTest(unittest.TestCase):
     def test_make_altstore(self):