An analogue to the Maven release process using Phing for PHP.

build.xml

<project name="some-php-project" default="main">
  <!-- this script requires http://pear.php.net/package/VersionControl_Git and https://pear.php.net/package/HTTP_Request2/ -->
  
  <!-- build.properties needs to contain 'nexus.username' and 'nexus.password' properties, MUST be .gitignore'd -->
  <property file="build.properties" />
	<property name="primary.repository" value="git@somewhere.com:group/some-php-project.git" override="false" />
	<property name="targetDir" value="target" override="true" />
	<property name="groupId" value="com/company/some-php-project" override="false"/>
	<property name="repositoryHost" value="https://someartifactrepo.company.com" override="false"/>
	
	<target name="clean">
		<delete dir="${targetDir}" failonerror="false"/>
	</target>
	
  <!-- Clones the primary repository into a temporary location -->
	<target name="release-clone" description="Clones the primary repository into a temporary directory" depends="clean">
		<gitclone repository="${primary.repository}" targetPath="${targetDir}/some-php-project" />
	</target>
	
	<!-- Creates a new version tag in the primary repository -->
	<target name="prepare" depends="release-clone" description="Creates a release tag in the remote repository">
		
		<!-- branch defaults to master if not specified -->
		<property name="branch" value="master" override="true" />
			
		<gitcheckout repository="${targetDir}/some-php-project" branchname="${branch}" />
		
		<gittag repository="${targetDir}/some-php-project" name="${version}" force="true" />
			
		<gitpush repository="${targetDir}/some-php-project" tags="true" force="true" />
		
	</target>
	
	<!-- Releases a version to artifact repository -->
	<target name="release" depends="release-clone" description="Clones primary repository into temporary directory, checks out a release tag, and uploads to artifact repository">
		
		<property name="releaseFilename" value="${phing.project.name}-${version}.tar.gz" />
		
		<gitcheckout repository="${targetDir}/some-php-project" branchname="${version}" />
		
		<!-- simple script to export git and project version into a properties file, included in the project -->
		<exec dir="${targetDir}/some-php-project" command="php buildNumbers.php" passthru="true" checkreturn="true"/>
		
		<tar destfile="${targetDir}/${releaseFilename}" compression="gzip" >
		  <!-- src/site contains the site code -->
			<fileset dir="${targetDir}/some-php-project/src/site">
				<exclude name="configuration.ini"/>
			</fileset>
		</tar>
		
		<exec dir="${targetDir}" passthru="true" checkreturn="true"
			command="curl -v --fail -X PUT -u ${nexus.username}:${nexus.password} --upload-file ${releaseFilename} ${repositoryHost}/maven/content/repositories/private-releases/${groupId}/${version}/${releaseFilename}" />
				
	</target>
</project>

Credit to @ahoffmann-wi for the development of the technique!