commit 6223549e4d5e1d442a9cfb8e8c7334bcc62c1662
Author: Maarten de Vries <maarten@de-vri.es>
Date:   Thu Jan 17 16:00:14 2019 +0100

    Remove `signals` from find_package(Boost COMPONENTS ...).
    
    tf2 is using signals2, which is not the same library.
    Additionally, signals2 has always been header only, and header only
    libraries must not be listed in find_package.
    
    Boost 1.69 removed the old signals library entirely, so the otherwise
    useless `COMPONENTS signals` actually breaks the build.

diff --git a/tf2/CMakeLists.txt b/tf2/CMakeLists.txt
index 9ffb17a..7a6da34 100644
--- a/tf2/CMakeLists.txt
+++ b/tf2/CMakeLists.txt
@@ -3,7 +3,7 @@ project(tf2)
 
 find_package(console_bridge REQUIRED)
 find_package(catkin REQUIRED COMPONENTS geometry_msgs rostime tf2_msgs)
-find_package(Boost REQUIRED COMPONENTS signals system thread)
+find_package(Boost REQUIRED COMPONENTS system thread)
 
 catkin_package(
    INCLUDE_DIRS include