Boost headers are used...

yaml-cpp.spec

@@ -9,6 +9,7 @@ URL:            https://github.com/jbeder/yaml-cpp
 Source0:        https://github.com/jbeder/yaml-cpp/archive/%{name}-%{version}.tar.gz
 
 BuildRequires:  cmake gcc-c++
+BuildRequires:  boost-devel
 
 %description
 yaml-cpp is a YAML parser and emitter in C++ written around the YAML 1.2 spec.
@@ -20,6 +21,7 @@ Group:          Development/Libraries
 License:        MIT
 Requires:       %{name}%{?_isa} = %{version}-%{release}
 Requires:       pkgconfig
+Requires:       boost-devel
 
 %description    devel
 The %{name}-devel package contains libraries and header files for
@@ -65,7 +67,6 @@ install -pm 0644 yaml-cpp-config{,-version}.cmake \
 %changelog
 * Wed Jan 31 2018 Richard Shaw <hobbes1069@gmail.com> - 0.5.3-9
 - Install yaml cmake files, fixes RHBZ#1509421.
-- Boost is no longer needed since 0.5.3.
 
 * Tue Jan 23 2018 Jonathan Wakely <jwakely@redhat.com> - 0.5.3-8
 - Rebuilt for Boost 1.66