device failures do not cause buildstream failures

Running bst build bootstrap/bash.bst on wsl with a windows container throws a permission failure while trying to open the fuse device but this does not seem to cause an error at the buildstream level. This seems like a fatal error and I'd expect that to be communicated to buildstream.

[--:--:--][e07b42b9][   build:bootstrap/freedesktop-junction.bst:bootstrap/build/debugedit-build.bst] START   Staging dependencies
[--:--:--][04eea704][    pull:bootstrap/freedesktop-junction.bst:bootstrap/libstdc++-stage1.bst] START   freedesktop-sdk/bootstrap-libstdc++-stage1/04eea704-pull.57301.log
[--:--:--][04eea704][    pull:bootstrap/freedesktop-junction.bst:bootstrap/libstdc++-stage1.bst] STATUS  Pulling artifact 04eea704 <- http://artifact_cache:11002
[--:--:--][04eea704][    pull:bootstrap/freedesktop-junction.bst:bootstrap/libstdc++-stage1.bst] INFO    Remote (http://artifact_cache:11002) does not have artifact 04eea704 cached
[00:00:00][04eea704][    pull:bootstrap/freedesktop-junction.bst:bootstrap/libstdc++-stage1.bst] SKIPPED Pull
==================================================================== 00:00:06 buildstream-demo (14/30) ====================================================================
                                                (Pull:0 12 0)→ (Fetch:0 12 0)→ (Build:0 0 0)→ (Push:0 0 0)→ (Src-push:0 0 0)
                                                                   ~~~~~~ cache: 3.3G / 44.4G (7%) ~~~~~~
[00:00:00][Build:bootstrap/freedesktop-junction.bst:bootstrap/build/debugedit-build.bst] [00:00:00][Pull:bootstrap/freedesktop-junction.bst:bootstrap/libstdc++-stage1.bst]
fuse: failed to open /dev/fuse: Permission denied
Process Process-18:1:
Traceback (most recent call last):
  File "/usr/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
    self.run()
  File "/usr/lib/python3.7/multiprocessing/process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.7/dist-packages/buildstream/_fuse/mount.py", line 191, in __run_fuse
[00:00:00][e07b42b9][   build:bootstrap/freedesktop-junction.bst:bootstrap/build/debugedit-build.bst] SUCCESS Staging dependencies