Increment RC number to RC 4 to match commits on branch.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e83abf7..1eb558b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -329,7 +329,7 @@
 SET(CMake_VERSION_MAJOR 2)
 SET(CMake_VERSION_MINOR 8)
 SET(CMake_VERSION_PATCH 1)
-SET(CMake_VERSION_RC 3)
+SET(CMake_VERSION_RC 4)
 
 # We use odd minor numbers for development versions.
 # Use a date for the development patch level.