[test/spec] More test cases for $(< file).

This is a curious construct described in issue #273.  It works in
multiple shells.

Also fix lint error, to fix the build.

osh/word_eval.py

@@ -30,7 +30,6 @@
 from core import error
 from core import passwd
 from core import pyutil
-from core import state
 from core.util import log, e_die, e_strict
 from frontend import consts
 from frontend import match

spec/process-sub.test.sh

@@ -44,3 +44,25 @@ warning: e2
 o2
 o1
 ## END
+
+#### $(<file) idiom with process sub
+echo FOO >foo
+
+# works in bash and zsh
+echo $(<foo)
+
+# this works in zsh, but not in bash
+tr A-Z a-z < <(<foo)
+
+cat < <(<foo; echo hi)
+
+## STDOUT:
+FOO
+hi
+## END
+## OK zsh STDOUT:
+FOO
+foo
+FOO
+hi
+## END

spec/redirect.test.sh

@@ -455,32 +455,57 @@ status=0
 echo FOO > myfile
 foo=$(< myfile)
 echo $foo
+## STDOUT:
+FOO
+## END
+## N-I dash/ash/yash stdout-json: "\n"
+
+#### $(< file) with more statements
 
 # note that it doesn't do this without a command sub!
 # It's apparently a special case in bash, mksh, and zsh?
 foo=$(echo begin; < myfile)
 echo $foo
+echo ---
 
 foo=$(< myfile; echo end)
 echo $foo
+echo ---
+
+foo=$(< myfile; <myfile)
+echo $foo
+echo ---
 
 ## STDOUT:
-FOO
 begin
+---
 end
-## END
-## N-I dash/ash/yash STDOUT:
+---
 
-begin
-end
+---
 ## END
-
 # weird, zsh behaves differently
 ## OK zsh STDOUT:
-FOO
 begin
 FOO
+---
+FOO
+end
+---
+FOO
 FOO
+---
+## END
+
+
+#### < file in pipeline and subshell doesn't work
+echo FOO > file2
+
+# This only happens in command subs, which is weird
+< file2 | tr A-Z a-z
+( < file2 )
+echo end
+## STDOUT:
 end
 ## END
 

test/spec.sh

@@ -692,7 +692,7 @@ regex() {
 
 process-sub() {
   # mksh and dash don't support it
-  sh-spec spec/process-sub.test.sh \
+  sh-spec spec/process-sub.test.sh --osh-failures-allowed 1 \
     $BASH $ZSH $OSH_LIST "$@"
 }