NullPointerException in AST diff

[tsantalis]

[pool-1-thread-1] INFO org.refactoringminer.rm1.GitHistoryRefactoringMinerImpl - Processing https://github.com/apache/drill.git c1b847acdc8cb90a1498b236b3bb5c81ca75c044 ...
[pool-1-thread-1] INFO org.refactoringminer.astDiff.matchers.ProjectASTDiffer - ModelDiff.getRefactorings() execution time: 2 seconds
[pool-1-thread-1] WARN org.refactoringminer.rm1.GitHistoryRefactoringMinerImpl - Ignored revision c1b847acdc8cb90a1498b236b3bb5c81ca75c044 due to error
java.lang.NullPointerException: Cannot invoke "com.github.gumtreediff.tree.Tree.getType()" because "srcInput" is null
at org.refactoringminer.astDiff.matchers.wrappers.RefactoringMatcher.processRefactorings(RefactoringMatcher.java:240)
at org.refactoringminer.astDiff.matchers.wrappers.RefactoringMatcher.matchAndUpdateOptimizationStore(RefactoringMatcher.java:44)
at org.refactoringminer.astDiff.matchers.wrappers.OptimizationAwareMatcher.match(OptimizationAwareMatcher.java:38)
at org.refactoringminer.astDiff.matchers.wrappers.ClassDiffMatcher.classDiffMatcher(ClassDiffMatcher.java:56)
at org.refactoringminer.astDiff.matchers.wrappers.ClassDiffMatcher.matchAndUpdateOptimizationStore(ClassDiffMatcher.java:34)
at org.refactoringminer.astDiff.matchers.wrappers.OptimizationAwareMatcher.match(OptimizationAwareMatcher.java:38)
at org.refactoringminer.astDiff.matchers.ProjectASTDiffer.process(ProjectASTDiffer.java:206)
at org.refactoringminer.astDiff.matchers.ProjectASTDiffer.makeASTDiff(ProjectASTDiffer.java:165)
at org.refactoringminer.astDiff.matchers.ProjectASTDiffer.diff(ProjectASTDiffer.java:69)
at org.refactoringminer.astDiff.matchers.ProjectASTDiffer.(ProjectASTDiffer.java:47)