Fixed bug preventing from building changelog

closes #11
6 jobs for master
Status Job ID Name Coverage
  Test
passed #360
Linux
clang-c++11

00:12:31

passed #362
Linux
clang-c++98

00:09:20

passed #359
Linux
gcc-c++11

00:19:57

passed #361
Linux
gcc-c++98

00:12:45

passed #363
Apple
macos-c++11

00:06:23

passed #364
Apple
macos-c++98

00:06:00