tracd incorrectly says "needs to be upgraded" if an exception is raised from needs_upgrade()

[Jun Omae]

Environment.needs_upgrade() raised a TypeError because installed plugin has incompatible method with Trac 1.3.x:

TypeError: environment_needs_upgrade() takes exactly 2 arguments (1 given)

When the error is raised, I get "needs to be upgraded" from tracd. It's incorrect, because the Trac environment is up-to-date.

Trac Error

TracError: The Trac Environment needs to be upgraded. Run:

  trac-admin "/home/jun66j5/var/trac/1.3-sqlite" upgrade

It seems the behavior is introduced in [15939] (#12680).

I consider that we should raise a TracError with Unable to check for upgrade message when an exception is raised from needs_upgrade():

trac/env.py

@@ -857 +857 @@
                 CacheManager(env).reset_metadata()
     else:
         env = Environment(env_path)
-        needs_upgrade = True
         try:
             needs_upgrade = env.needs_upgrade()
+        except TracError as e:
+            env.log.error("Exception caught while checking for upgrade: %s",
+                          exception_to_unicode(e))
+            raise
         except Exception as e:  # e.g. no database connection
             env.log.error("Exception caught while checking for upgrade: %s",
                           exception_to_unicode(e, traceback=True))
-        if needs_upgrade:
-            raise TracError(_('The Trac Environment needs to be upgraded. '
-                              'Run:\n\n  trac-admin "%(path)s" upgrade',
-                              path=env_path))
+            raise TracError(_("Unable to check for upgrade: %(err)s",
+                              err=exception_to_unicode(e)))
+        else:
+            if needs_upgrade:
+                raise TracError(_('The Trac Environment needs to be upgraded. '
+                                  'Run:\n\n  trac-admin "%(path)s" upgrade',
+                                  path=env_path))
 
     return env
 

After the patch, tracd says in this case:

Trac Error

TracError: Unable to check for upgrade: TypeError: environment_needs_upgrade() takes exactly 2 arguments (1 given)}