Merge branch '1.2.x'

Author: wilkinsona

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/ApplicationPidFileWriter.java

@@ -108,7 +108,7 @@ public void onApplicationEvent(SpringApplicationEvent event) {
 writePidFile(event);
 }
 catch (Exception ex) {
-logger.warn(String.format("Cannot create pid file %s", this.file));
+logger.warn(String.format("Cannot create pid file %s", this.file), ex);
 }
 }
 }