Hi, All.  It appears that httpd24-libnghttp2 is missing from SL6.  This prevents yum updates on systems that have httpd24-httpd or any httpd24 modules installed.

For example:
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yum update httpd24-httpd
Loaded plugins: priorities, security
Setting up Update Process
...
--> Finished Dependency Resolution
Error: Package: httpd24-httpd-2.4.18-11.sl6.x86_64 (softwarecollections)
           Requires: libnghttp2-httpd24.so.14()(64bit)
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest
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And in particular:
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================================================================================
Package Arch Version Repository Size
================================================================================
Removing:
httpd24-httpd x86_64 2.4.12-4.sl6.2 @softwarecollections/6.6 3.6 M
Removing for dependencies:
httpd24-httpd-devel x86_64 2.4.12-4.sl6.2 @softwarecollections/6.6 770 k
perl516-mod_perl x86_64 2.0.8-5.20130221svn1448242.el6
@softwarecollections/6.5 6.0 M
perl516-mod_perl-devel x86_64 2.0.8-5.20130221svn1448242.el6
@softwarecollections/6.5 917 k
python27-mod_wsgi x86_64 3.4-12.el6 @softwarecollections/6.5 199 k
python33-mod_wsgi x86_64 3.4-14.el6 @softwarecollections/6.5 203 k
ruby193-mod_passenger40 x86_64 4.0.18-11.el6 @softwarecollections/6.5 566 k

Transaction Summary
================================================================================
Remove 7 Package(s)
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For what it's worth, it is available from the centos repo at:
http://mirror.centos.org/centos/6/sclo/x86_64/rh/httpd24/httpd24-libnghttp2-1.7.1-1.el6.x86_64.rpm

Many thanks,
Devin