Merge pull request #1040 from peter1000/patch-1

Fixes typo
diff --git a/src/build_log.h b/src/build_log.h
index fe81a85..785961e 100644
--- a/src/build_log.h
+++ b/src/build_log.h
@@ -27,7 +27,7 @@
 
 /// Can answer questions about the manifest for the BuildLog.
 struct BuildLogUser {
-  /// Return if a given output no longer part of the build manifest.
+  /// Return if a given output is no longer part of the build manifest.
   /// This is only called during recompaction and doesn't have to be fast.
   virtual bool IsPathDead(StringPiece s) const = 0;
 };