hush: fix bug with local environment vars in pipes; simplify parse_stream()

function                                             old     new   delta
parse_stream                                        1238    1218     -20
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-20)             Total: -20 bytes

1 files changed, 7 insertions, 0 deletions

diff --git a/shell/hush_test/hush-vars/var_in_pipes.tests b/shell/hush_test/hush-vars/var_in_pipes.tests
new file mode 100755
index 000000000..3f8cd2729
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_in_pipes.tests
@@ -0,0 +1,7 @@
+b=1 env | grep ^b=
+true | b=2 env | grep ^b=
+a=1 true | b=3 env | grep ^b=
+
+(b=4 env) | grep ^b=
+(true | b=5 env) | grep ^b=
+(a=1 true | b=6 env) | grep ^b=