Created attachment 1203177 [details]
Expect reproducer

Description of problem:
When I run spawn cat $LONG_TEXT_FILE in expect, expect do not print the whole file but its output is somehow truncated. 

I am attaching reproducer of this issue.

Version-Release number of selected component (if applicable):
expect-5.45-14.el7_1.aarch64

How reproducible:
Always

Steps to Reproduce:
1. run expect_reproducer $ ./expect_reproducer

Actual results:

spawn cat cus.log
core_backtrace: 1
:{   "signal": 11
:,   "executable": "/usr/bin/will_segfault"
:,   "stacktrace":

...

:              , {   "address": 4396484134880
:                ,   "build_id": "42cc8b40c4454279e954617a3217dc37e9d4ed62"
:                ,   "build_id_offset": 2016


Expected results:

spawn cat cus.log
core_backtrace: 1
:{   "signal": 11
:,   "executable": "/usr/bin/will_segfault"
:,   "stacktrace":

...

:        } ]
:}
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