[racket] Amazon Linux update causes `require' in 5.1.1 to hang indefinitely?

Yesterday I ran `yum update' on an Amazon Linux 32-bit instance. It
updated quite a bit more than I expected.

yum.log:
Jul 10 00:20:23 Updated: tzdata-2011d-3.9.amzn1.noarch
Jul 10 00:20:24 Updated: tzdata-java-2011d-3.9.amzn1.noarch
Jul 10 00:20:24 Updated: system-release-2011.02-1.8.noarch
Jul 10 00:20:24 Updated: nss-softokn-freebl-3.12.9-3.12.amzn1.i686
Jul 10 00:20:29 Updated: glibc-2.12-1.7.26.amzn1.i686
Jul 10 00:20:43 Updated: glibc-common-2.12-1.7.26.amzn1.i686
Jul 10 00:20:44 Updated: krb5-libs-1.9-9.17.amzn1.i686
Jul 10 00:20:44 Updated: nspr-4.8.7-1.10.amzn1.i686
Jul 10 00:20:44 Updated: nss-util-3.12.9-1.8.amzn1.i686
Jul 10 00:20:44 Updated: openssl-1.0.0a-4.1.10.amzn1.i686
Jul 10 00:20:51 Updated: 1:java-1.6.0-openjdk-1.6.0.0-52.1.9.8.34.amzn1.i686
Jul 10 00:20:51 Updated: 32:bind-libs-9.7.3-2.9.amzn1.i686
Jul 10 00:20:51 Updated: nss-softokn-3.12.9-3.12.amzn1.i686
Jul 10 00:20:52 Updated: nss-3.12.9-9.20.amzn1.i686
Jul 10 00:20:52 Updated: nss-sysinit-3.12.9-9.20.amzn1.i686
Jul 10 00:20:52 Updated: libcurl-7.19.7-26.19.amzn1.i686
Jul 10 00:20:52 Updated: krb5-devel-1.9-9.17.amzn1.i686
Jul 10 00:20:52 Updated: 1:perl-Pod-Escapes-1.04-119.11.amzn1.i686
Jul 10 00:20:53 Updated: 1:perl-Module-Pluggable-3.90-119.11.amzn1.i686
Jul 10 00:20:53 Updated: 4:perl-libs-5.10.1-119.11.amzn1.i686
Jul 10 00:20:53 Updated: 3:perl-version-0.77-119.11.amzn1.i686
Jul 10 00:20:53 Updated: 1:perl-Pod-Simple-3.13-119.11.amzn1.i686
Jul 10 00:20:58 Updated: 4:perl-5.10.1-119.11.amzn1.i686
Jul 10 00:20:58 Updated: perl-Compress-Raw-Zlib-2.023-119.11.amzn1.i686
Jul 10 00:20:58 Updated: 1:perl-Digest-SHA-5.47-119.11.amzn1.i686
Jul 10 00:20:58 Installed: libffi-3.0.5-3.2.2.amzn1.i686
Jul 10 00:20:58 Updated: python26-libs-2.6.7-1.36.amzn1.i686
Jul 10 00:21:02 Updated: python26-2.6.7-1.36.amzn1.i686
Jul 10 00:21:02 Updated: curl-7.19.7-26.19.amzn1.i686
Jul 10 00:21:02 Updated: 32:bind-utils-9.7.3-2.9.amzn1.i686
Jul 10 00:21:03 Updated: krb5-workstation-1.9-9.17.amzn1.i686
Jul 10 00:21:03 Updated: cpio-2.10-9.9.amzn1.i686
Jul 10 00:21:03 Updated: logrotate-3.7.8-12.8.amzn1.i686
Jul 10 00:21:03 Updated: sudo-1.7.4p5-5.10.amzn1.i686
Jul 10 00:21:03 Updated: libnl-1.1-12.6.amzn1.i686
Jul 10 00:21:03 Updated: 12:dhclient-4.1.1-12.P1.11.amzn1.i686
Jul 10 00:21:04 Updated: perl-Test-Harness-3.17-119.11.amzn1.i686
Jul 10 00:21:04 Updated: 1:perl-ExtUtils-ParseXS-2.2003.0-119.11.amzn1.i686
Jul 10 00:21:04 Updated: 4:perl-devel-5.10.1-119.11.amzn1.i686
Jul 10 00:21:05 Updated: perl-ExtUtils-MakeMaker-6.55-119.11.amzn1.i686
Jul 10 00:21:05 Updated: perl-IO-Compress-Base-2.020-119.11.amzn1.i686
Jul 10 00:21:05 Updated: perl-IO-Compress-Zlib-2.020-119.11.amzn1.i686
Jul 10 00:21:06 Updated: glibc-headers-2.12-1.7.26.amzn1.i686
Jul 10 00:21:06 Updated: glibc-devel-2.12-1.7.26.amzn1.i686
Jul 10 00:21:06 Updated: perl-Compress-Zlib-2.020-119.11.amzn1.i686
Jul 10 00:21:06 Updated: perl-CPAN-1.9402-119.11.amzn1.i686
Jul 10 00:21:08 Updated: openssl-devel-1.0.0a-4.1.10.amzn1.i686
Jul 10 00:21:10 Updated: aws-apitools-elb-1.0.12.0-1.0.amzn1.noarch
Jul 10 00:21:20 Updated: aws-apitools-ec2-1.4.3.0-1.2.amzn1.noarch

Racket continued to work fine at first. Later, I did a reboot of the
system. Now, any racket program seems to "hang" using 99% of the CPU
when launched. Simplest example:

$ racket
Welcome to Racket v5.1.1.
> (displayln "hello")
hello
> (require racket/date)

At this point it becomes non-responsive, even to C-c. It can't be
killed with `sudo kill <pid>'. It will only die with `sudo kill -9
<pid>'.

Note that it doesn't seem to matter what I require (could be
racket/date, rackunit, etc.), it's the `require' itself that seems to
be broken.

Seemingly one of the packages above caused the breakage.

I'll continue to try to figure this out on my own, but thought I'd
post in case someone might quickly realize "oh it's probably X".

Thank you.