NullPointerError while doing a build

[endobson]

Repro steps:

git clone https://shekari@bitbucket.org/snippets/shekari/7ryL7/bazel-genrule-issue.git issue
cd issue
git co 6480b0b0d5a3171755826ff409e81ae2dc384f8c
cd repo2
bazel build //...

The contents of repo2 should just be a workspace file with the following content:

git_repository(
  name = "repo1",
  remote = "https://bitbucket.org/snippets/shekari/7ryL7/bazel-genrule-issue.git"
  commit = "68d3656952703e3200e87dc6a5204cb42a2a63dd"
)

This may be because the repository doesn't have a WORKSPACE file at the root.

Output:

Unhandled exception thrown during build; message: Unrecoverable error while evaluating node 'WORKSPACE_FILE:[/Users/endobson/tmp/issue/repo2]/[WORKSPACE]' (requested by nodes 'PACKAGE:external')
INFO: Elapsed time: 0.453s
java.lang.RuntimeException: Unrecoverable error while evaluating node 'WORKSPACE_FILE:[/Users/endobson/tmp/issue/repo2]/[WORKSPACE]' (requested by nodes 'PACKAGE:external')
        at com.google.devtools.build.skyframe.ParallelEvaluator$Evaluate.run(ParallelEvaluator.java:982)
        at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:499)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
        at com.google.devtools.build.lib.packages.WorkspaceFactory.setImportedExtensions(WorkspaceFactory.java:157)
        at com.google.devtools.build.lib.skyframe.WorkspaceFileFunction.loadSkylarkImports(WorkspaceFileFunction.java:116)
        at com.google.devtools.build.lib.skyframe.WorkspaceFileFunction.parse(WorkspaceFileFunction.java:123)
        at com.google.devtools.build.lib.skyframe.WorkspaceFileFunction.compute(WorkspaceFileFunction.java:90)
        at com.google.devtools.build.skyframe.ParallelEvaluator$Evaluate.run(ParallelEvaluator.java:933)
        ... 4 more

bazel version

endobson@yggdrasil () ~/tmp/issue/repo2 % bazel version                                                                                                                                                                                (2)
.......
Build label: head (@b190ab0)
Build target: bazel-out/local_darwin-fastbuild/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Fri Feb 12 09:10:36 2016 (1455268236)
Build timestamp: 1455268236
Build timestamp as int: 1455268236

[endobson]

Turns out that actually building from HEAD instead of just downloading HEAD and staying on the old checkout is not a good idea. I cannot reproduce with the version at HEAD.