Running "git skara webrev" fails with the following exception/stack trace:

$ git skara webrev
Exception in thread "main" java.nio.file.FileSystemException: /.../.merge_file_d0aaTx: Operation not permitted
at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:100)
at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:106)
at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
at java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
at java.base/java.nio.file.Files.newByteChannel(Files.java:380)
at java.base/java.nio.file.Files.newByteChannel(Files.java:432)
at java.base/java.nio.file.Files.readAllBytes(Files.java:3288)
at org.openjdk.skara.vcs/org.openjdk.skara.vcs.git.GitRepository.show(GitRepository.java:1136)
at org.openjdk.skara.vcs/org.openjdk.skara.vcs.ReadOnlyRepository.lines(ReadOnlyRepository.java:112)
at org.openjdk.skara.webrev/org.openjdk.skara.webrev.RemovedFileView.<init>(RemovedFileView.java:48)
at org.openjdk.skara.webrev/org.openjdk.skara.webrev.Webrev$Builder.generate(Webrev.java:400)
at org.openjdk.skara.webrev/org.openjdk.skara.webrev.Webrev$Builder.generate(Webrev.java:179)
at org.openjdk.skara.cli/org.openjdk.skara.cli.GitWebrev.generate(GitWebrev.java:470)
at org.openjdk.skara.args/org.openjdk.skara.args.Command.main(Command.java:54)
at org.openjdk.skara.args/org.openjdk.skara.args.MultiCommandParser.lambda$parse$3(MultiCommandParser.java:73)
at org.openjdk.skara.cli/org.openjdk.skara.cli.GitWebrev.main(GitWebrev.java:527)
at org.openjdk.skara.cli/org.openjdk.skara.cli.GitSkara.main(GitSkara.java:231)