Fix again for fffbcba0b. We should keep original env.update() return value type as list-of-docnames-that-ordered-in-order-to-read.

1 files changed, 2 insertions, 2 deletions

diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index 70ec6cb5..74cd6198 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -247,8 +247,8 @@ class Builder(object):
         # while reading, collect all warnings from docutils
         warnings = []
         self.env.set_warnfunc(lambda *args: warnings.append(args))
-        updated_docnames = self.env.update(self.config, self.srcdir,
-                                           self.doctreedir, self.app)
+        updated_docnames = set(self.env.update(self.config, self.srcdir,
+                                               self.doctreedir, self.app))
         self.env.set_warnfunc(self.warn)
         for warning in warnings:
             self.warn(*warning)