env won't run a command with an = in its name. This is documented as a bug, but it's easily fixed in a backwards compatible way.
Index: env.1 =================================================================== RCS file: /cvs/src/usr.bin/env/env.1,v retrieving revision 1.19 diff -u -p -r1.19 env.1 --- env.1 8 Mar 2014 01:42:17 -0000 1.19 +++ env.1 11 Jan 2015 17:32:32 -0000 @@ -119,9 +119,3 @@ specification. The historic .Fl option has been deprecated but is still supported in this implementation. -.Sh BUGS -.Nm -doesn't handle commands with equal -.Pq Sq = -signs in their -names, for obvious reasons. Index: env.c =================================================================== RCS file: /cvs/src/usr.bin/env/env.c,v retrieving revision 1.15 diff -u -p -r1.15 env.c --- env.c 8 Mar 2014 00:09:20 -0000 1.15 +++ env.c 11 Jan 2015 17:32:07 -0000 @@ -69,6 +69,8 @@ main(int argc, char *argv[]) err(126, "setenv"); } } + if (strcmp(*argv, "--") == 0) + argv++; if (*argv) { /*