[jenkins] Build PRs against upstream target branch

cleanup unused image tags; may want to switch away from Dockerfile to an
explicit container run at some point.

Jenkinsfile

@@ -1,4 +1,5 @@
-def triqsProject = '/TRIQS/triqs/' + env.BRANCH_NAME.replaceAll('/', '%2F')
+def triqsBranch = env.CHANGE_TARGET ?: env.BRANCH_NAME
+def triqsProject = '/TRIQS/triqs/' + triqsBranch.replaceAll('/', '%2F')
 
 properties([
   disableConcurrentBuilds(),
@@ -16,22 +17,22 @@ def platforms = [:]
 def dockerPlatforms = ["ubuntu-clang", "ubuntu-gcc", "centos-gcc"]
 for (int i = 0; i < dockerPlatforms.size(); i++) {
   def platform = dockerPlatforms[i]
-  platforms[platform] = { ->
-    stage(platform) {
-      timeout(time: 1, unit: 'HOURS') {
-	node('docker') {
-	  checkout scm
-	  /* construct a Dockerfile for this base */
-	  sh '''
-	    ( echo "FROM flatironinstitute/triqs:$BRANCH_NAME-$STAGE_NAME" ; sed '0,/^FROM /d' Dockerfile ) > Dockerfile.jenkins
-	    mv -f Dockerfile.jenkins Dockerfile
-	  '''
-	  /* build and tag */
-	  def img = docker.build("flatironinstitute/dft_tools:${env.BRANCH_NAME}-${env.STAGE_NAME}")
-	}
+  platforms[platform] = { -> stage(platform) {
+    timeout(time: 1, unit: 'HOURS') {
+      node('docker') {
+        checkout scm
+        /* construct a Dockerfile for this base */
+        sh """
+          ( echo "FROM flatironinstitute/triqs:${triqsBranch}-${env.STAGE_NAME}" ; sed '0,/^FROM /d' Dockerfile ) > Dockerfile.jenkins
+          mv -f Dockerfile.jenkins Dockerfile
+        """
+        /* build and tag */
+        def img = docker.build("flatironinstitute/dft_tools:${env.BRANCH_NAME}-${env.STAGE_NAME}")
+        /* but we don't need the tag so clean it up (alternatively, could refacter to run in container) */
+        sh "docker rmi ${img.imageName()}"
       }
     }
-  }
+  } }
 }
 
 def osxPlatforms = [
@@ -41,47 +42,45 @@ def osxPlatforms = [
 for (int i = 0; i < osxPlatforms.size(); i++) {
   def platformEnv = osxPlatforms[i]
   def platform = platformEnv[0]
-  platforms["osx-$platform"] = { ->
-    stage("osx-$platform") {
-      timeout(time: 1, unit: 'HOURS') {
-	node('osx && triqs') {
-	  def workDir = pwd()
-	  def tmpDir = pwd(tmp:true)
-	  def buildDir = "$tmpDir/build"
-	  def installDir = "$tmpDir/install"
+  platforms["osx-$platform"] = { -> stage("osx-$platform") {
+    timeout(time: 1, unit: 'HOURS') {
+      node('osx && triqs') {
+        def srcDir = pwd()
+        def tmpDir = pwd(tmp:true)
+        def buildDir = "$tmpDir/build"
+        def installDir = "$tmpDir/install"
 
-	  dir(installDir) {
-	    deleteDir()
-	  }
+        dir(installDir) {
+          deleteDir()
+        }
 
-	  copyArtifacts(projectName: triqsProject, selector: upstream(fallbackToLastSuccessful: true), filter: "osx-${platform}.zip")
-	  unzip(zipFile: "osx-${platform}.zip", dir: installDir)
-	  /* fixup zip-stripped permissions (JENKINS-13128) */
-	  sh "chmod +x $installDir/bin/*"
+        copyArtifacts(projectName: triqsProject, selector: upstream(fallbackToLastSuccessful: true), filter: "osx-${platform}.zip")
+        unzip(zipFile: "osx-${platform}.zip", dir: installDir)
+        /* fixup zip-stripped permissions (JENKINS-13128) */
+        sh "chmod +x $installDir/bin/*"
 
-	  checkout scm
+        checkout scm
 
-	  dir(buildDir) { withEnv(platformEnv[1]+[
-	      "PATH=$installDir/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin",
-	      "CPATH=$installDir/include",
-	      "LIBRARY_PATH=$installDir/lib",
-	      "CMAKE_PREFIX_PATH=$installDir/share/cmake"]) {
-	    deleteDir()
-	    sh "cmake $workDir -DTRIQS_ROOT=$installDir"
-	    sh "make -j2"
-	    try {
-	      sh "make test"
-	    } catch (exc) {
-	      archiveArtifacts(artifacts: 'Testing/Temporary/LastTest.log')
-	      throw exc
-	    }
-	    sh "make install"
-	  } }
-	  // zip(zipFile: "osx-${platform}.zip", archive: true, dir: installDir)
-	}
+        dir(buildDir) { withEnv(platformEnv[1]+[
+            "PATH=$installDir/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin",
+            "CPATH=$installDir/include",
+            "LIBRARY_PATH=$installDir/lib",
+            "CMAKE_PREFIX_PATH=$installDir/share/cmake"]) {
+          deleteDir()
+          sh "cmake $srcDir -DTRIQS_ROOT=$installDir"
+          sh "make -j2"
+          try {
+            sh "make test"
+          } catch (exc) {
+            archiveArtifacts(artifacts: 'Testing/Temporary/LastTest.log')
+            throw exc
+          }
+          sh "make install"
+        } }
+        // zip(zipFile: "osx-${platform}.zip", archive: true, dir: installDir)
       }
     }
-  }
+  } }
 }
 
 parallel platforms