Amazon Linux does not support systemd. Having the versioncmp makes this fail on newer versions (which do not yet support systemd). Run this on 2015.03 and you end up with an apache server that will not start.

cliles · Morgan Haskel · commit c054232b3986 · 2015-06-16T11:10:10.000-07:00
diff --git a/manifests/default_mods.pp b/manifests/default_mods.pp
@@ -12,7 +12,7 @@
       if versioncmp($apache_version, '2.4') >= 0 {
         # Lets fork it
         # Do not try to load mod_systemd on RHEL/CentOS 6 SCL.
-        if ( !($::osfamily == 'redhat' and versioncmp($::operatingsystemrelease, '7.0') == -1) and !($::operatingsystem == 'Amazon' and versioncmp($::operatingsystemrelease, '2014.09') <= 0  ) ) {
+        if ( !($::osfamily == 'redhat' and versioncmp($::operatingsystemrelease, '7.0') == -1) and !$::operatingsystem == 'Amazon' ) {
           ::apache::mod { 'systemd': }
         }
         ::apache::mod { 'unixd': }

Original file line number	Diff line number	Diff line change
`@@ -12,7 +12,7 @@`
`12`	`12`	`if versioncmp($apache_version, '2.4') >= 0 {`
`13`	`13`	`# Lets fork it`
`14`	`14`	`# Do not try to load mod_systemd on RHEL/CentOS 6 SCL.`
`15`		`- if ( !($::osfamily == 'redhat' and versioncmp($::operatingsystemrelease, '7.0') == -1) and !($::operatingsystem == 'Amazon' and versioncmp($::operatingsystemrelease, '2014.09') <= 0 ) ) {`
	`15`	`+ if ( !($::osfamily == 'redhat' and versioncmp($::operatingsystemrelease, '7.0') == -1) and !$::operatingsystem == 'Amazon' ) {`
`16`	`16`	`::apache::mod { 'systemd': }`
`17`	`17`	`}`
`18`	`18`	`::apache::mod { 'unixd': }`