cd /WRKOBJDIR/www/firefox/work/firefox-51.0.1/../build/dist/bin &&  \
     ./run-mozilla.sh /WRKOBJDIR/www/firefox/work/firefox-51.0.1/mach check-spidermonkey
env: python: No such file or directory
env: python: No such file or directory
Running jit-tests
running jstests
running jsapi-tests
Error running mach:

    ['check-spidermonkey']

The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.

You should consider filing a bug for this issue.

If filing a bug, please include the full output of mach, including this error
message.

The details of the failure are as follows:

OSError: [Errno 2] No such file or directory

  File "/WRKOBJDIR/www/firefox/work/firefox-51.0.1/testing/mach_commands.py", 
	line 450, in run_checkspidermonkey
    jsapi_tests_result = subprocess.call(jsapi_tests_cmd)
  File "/usr/pkg/lib/python2.7/subprocess.py", line 168, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/pkg/lib/python2.7/subprocess.py", line 390, in __init__
    errread, errwrite)
  File "/usr/pkg/lib/python2.7/subprocess.py", line 1024, in _execute_child
    raise child_exception
*** Error code 1

Stop.
make[1]: stopped in /usr/pkgsrc/www/firefox
*** Error code 1

Stop.
make: stopped in /usr/pkgsrc/www/firefox