Seen this exception that fails the execution.

Taken from https://ci.jenkins-ci.org/job/infra_extension-indexer/126/console

Exception in thread "main" java.lang.AssertionError: exec.getBuild().getPreviousBuildInProgress
    at com.sun.tools.javac.comp.Attr.selectSym(Attr.java:1995)
    at com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:1881)
    at com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:1538)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:390)
    at com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1288)
    at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1226)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:390)
    at com.sun.tools.javac.comp.Attr.visitVarDef(Attr.java:730)
    at com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:707)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:410)
    at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:426)
    at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:762)
    at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:755)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:410)
    at com.sun.tools.javac.comp.Attr.visitWhileLoop(Attr.java:776)
    at com.sun.tools.javac.tree.JCTree$JCWhileLoop.accept(JCTree.java:803)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:410)
    at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:426)
    at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:762)
    at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:755)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:410)
    at com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:681)
    at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:655)
    at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:373)
    at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:410)
    at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2741)
    at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2667)
    at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2603)
    at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1051)
    at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1027)
    at com.sun.tools.javac.api.JavacTaskImpl.analyze(JavacTaskImpl.java:369)
    at com.sun.tools.javac.api.JavacTaskImpl.analyze(JavacTaskImpl.java:349)
    at org.jenkinsci.extension_indexer.ExtensionPointsExtractor.extract(ExtensionPointsExtractor.java:79)
    at org.jenkinsci.extension_indexer.ExtensionPointsExtractor.extract(ExtensionPointsExtractor.java:48)
    at org.jenkinsci.extension_indexer.ExtensionPointListGenerator.discover(ExtensionPointListGenerator.java:300)
    at org.jenkinsci.extension_indexer.ExtensionPointListGenerator.run(ExtensionPointListGenerator.java:163)
    at org.jenkinsci.extension_indexer.ExtensionPointListGenerator.main(ExtensionPointListGenerator.java:148)