hammer tries to run wget without checking if it's installed

Tried to run hammer on FreeBSD 11.3. It tried to run wget without checking if it's installed. Should print a nice error, rather than this confusing exception:

$ ./hammer.py prepare-system -p local
[HAMMER]  2019-08-08 10:17:55,786 Enabled features: unittest docs install perfdhcp
[HAMMER]  2019-08-08 10:17:55,806 Preparing deps for freebsd 11.3-RELEASE-p2
[HAMMER]  2019-08-08 10:17:55,807 >>>>> Executing wget --no-verbose -O /tmp/gtest.tar.gz https://github.com/google/googletest/archive/release-1.8.0.tar.gz in /usr/home/jenkins/workspace/kea-master-cppcheck-internal
/bin/sh: wget: not found
Traceback (most recent call last):
  File "./hammer.py", line 2145, in <module>
    main()
  File "./hammer.py", line 2125, in main
    prepare_system_cmd(args)
  File "./hammer.py", line 2023, in prepare_system_cmd
    prepare_system_local(features, args.check_times)
  File "./hammer.py", line 1261, in prepare_system_local
    _install_gtest_sources()
  File "./hammer.py", line 821, in _install_gtest_sources
    execute(cmd)
  File "./hammer.py", line 275, in execute
    raise ExecutionError("The command return non-zero exitcode %s, cmd: '%s'" % (exitcode, cmd))
__main__.ExecutionError: The command return non-zero exitcode 127, cmd: 'wget --no-verbose -O /tmp/gtest.tar.gz https://github.com/google/googletest/archive/release-1.8.0.tar.gz'
$ wget
-sh: wget: not found