Comment # 3 on bug 1087718 from Christian Wittmer

sorry but the package is building for Leap 15 and last package change was 8
month ago ... 

but you can take package from repo X11:RemoteDesktop

zypper ar 

http://download.opensuse.org/repositories/X11:/RemoteDesktop/openSUSE_Leap_15.0/
X11_RemoteDesktop

or download just the rpm:
http://download.opensuse.org/repositories/X11:/RemoteDesktop/openSUSE_Leap_15.0/x86_64/rdesktop-1.8.3-lp150.87.1.x86_64.rpm