$ bazel build //...
........
INFO: Found 42 targets...
Unhandled exception thrown during build; message: Multiple entries with same key: =/Users/bstaffin/src and =/Users/bstaffin/src
INFO: Elapsed time: 3.933s
java.lang.IllegalArgumentException: Multiple entries with same key: =/Users/bstaffin/src and =/Users/bstaffin/src
	at com.google.common.collect.ImmutableMap.checkNoConflict(ImmutableMap.java:136)
	at com.google.common.collect.RegularImmutableMap.checkNoConflictInKeyBucket(RegularImmutableMap.java:98)
	at com.google.common.collect.RegularImmutableMap.fromEntryArray(RegularImmutableMap.java:84)
	at com.google.common.collect.ImmutableMap$Builder.build(ImmutableMap.java:295)
	at com.google.devtools.build.lib.buildtool.BuildTool.transformPackageRoots(BuildTool.java:301)
	at com.google.devtools.build.lib.buildtool.BuildTool.buildTargets(BuildTool.java:209)
	at com.google.devtools.build.lib.buildtool.BuildTool.processRequest(BuildTool.java:334)
	at com.google.devtools.build.lib.runtime.commands.BuildCommand.exec(BuildCommand.java:71)
	at com.google.devtools.build.lib.runtime.BlazeCommandDispatcher.exec(BlazeCommandDispatcher.java:371)
	at com.google.devtools.build.lib.runtime.BlazeRuntime$3.exec(BlazeRuntime.java:1021)
	at com.google.devtools.build.lib.server.RPCService.executeRequest(RPCService.java:65)
	at com.google.devtools.build.lib.server.RPCServer.executeRequest(RPCServer.java:434)
	at com.google.devtools.build.lib.server.RPCServer.serve(RPCServer.java:229)
	at com.google.devtools.build.lib.runtime.BlazeRuntime.serverMain(BlazeRuntime.java:976)
	at com.google.devtools.build.lib.runtime.BlazeRuntime.main(BlazeRuntime.java:773)
	at com.google.devtools.build.lib.bazel.BazelMain.main(BazelMain.java:55)