pipelineStages in Assets makes the build hang

[codeape]

If I the build with Assets := Seq(rjs) the build can finish but if I run pipelineStages in Assets := Seq(rjs) the build hangs after updating (every time):

sbt front/compile
[info] Loading global plugins from /home/codeape/.sbt/0.13/plugins
[info] Loading project definition from /home/codeape/src/git/cronus/project
[info] Set current project to cronus (in build file:/home/codeape/src/git/cronus/)
[info] Updating {file:/home/codeape/src/git/cronus/}cronusw...
[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.
[info] Updating {file:/home/codeape/src/git/cronus/}common...
[info] Resolving com.fasterxml.jackson.module#jackson-module-scala_2.11;2.4.4 ..[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.
[info] Updating {file:/home/codeape/src/git/cronus/}front...
[info] Resolving com.fasterxml.jackson.module#jackson-module-scala_2.11;2.4.4 ..[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.

When I look at the process tree it looks like this

pstree -a 5381
sbt /home/codeape/bin/sbt front/compile
  └─java -Xms512M -Xmx1536M -Xss1M -XX:+CMSClassUnloadingEnabled -jar /home/codeape/bin/sbt-launch.jar front/compile
      └─16*[{java}]

16 threads hanging.

[codeape]

Here is a branch on my project where it is 100% reproducible for me (on Linux):
https://github.com/codeape/cronus/tree/sbt-web-bug

Run sbt front/compile on my sbt-web-bug branch.

[mkurz]

Not sure if this is still happening, but maybe #169 resolved this problem since we don't rely on akka and dispatchers anymore but use a pure blocking approach. If someone experiences problems with sbt 1.5.0 (soon to be released) please comment here, thanks!