dask: CI test failures with pyarrow and hdfs

=================================== FAILURES ===================================
_________________________ test_parquet_pyarrow[hdfs3] __________________________
mod_name = 'pyarrow', error_msg = '`pyarrow` not installed'
    def import_required(mod_name, error_msg):
        """Attempt to import a required dependency.
    
        Raises a RuntimeError if the requested module is not available.
        """
        try:
>           return import_module(mod_name)
dask/utils.py:92: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'pyarrow', package = None
    def import_module(name, package=None):
        """Import a module.
    
        The 'package' argument is required when performing a relative import. It
        specifies the package to use as the anchor point from which to resolve the
        relative import to an absolute import.
    
        """
        level = 0
        if name.startswith('.'):
            if not package:
                msg = ("the 'package' argument is required to perform a relative "
                       "import for {!r}")
                raise TypeError(msg.format(name))
            for character in name:
                if character != '.':
                    break
                level += 1
>       return _bootstrap._gcd_import(name[level:], package, level)
/opt/conda/lib/python3.6/importlib/__init__.py:126: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'pyarrow', package = None, level = 0
>   ???
<frozen importlib._bootstrap>:994: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'pyarrow', import_ = <function _gcd_import at 0x7f105ba66e18>
>   ???
<frozen importlib._bootstrap>:971: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
name = 'pyarrow', import_ = <function _gcd_import at 0x7f105ba66e18>
>   ???
<frozen importlib._bootstrap>:955: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
spec = ModuleSpec(name='pyarrow', loader=<_frozen_importlib_external.SourceFileLoader object at 0x7f102ff02c50>, origin='/opt...n3.6/site-packages/pyarrow/__init__.py', submodule_search_locations=['/opt/conda/lib/python3.6/site-packages/pyarrow'])
>   ???
<frozen importlib._bootstrap>:665: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <_frozen_importlib_external.SourceFileLoader object at 0x7f102ff02c50>
module = <module 'pyarrow' from '/opt/conda/lib/python3.6/site-packages/pyarrow/__init__.py'>
>   ???
<frozen importlib._bootstrap_external>:678: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
f = <built-in function exec>
args = (<code object <module> at 0x7f102fef2c00, file "/opt/conda/lib/python3.6/site-packages/pyarrow/__init__.py", line 20>,...cached__': '/opt/conda/lib/python3.6/site-packages/pyarrow/__pycache__/__init__.cpython-36.pyc', '__doc__': None, ...})
kwds = {}
>   ???
<frozen importlib._bootstrap>:219: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
    from pkg_resources import get_distribution, DistributionNotFound
    try:
        __version__ = get_distribution(__name__).version
    except DistributionNotFound:
       # package is not installed
        try:
            # This code is duplicated from setup.py to avoid a dependency on each
            # other.
            def parse_version(root):
                from setuptools_scm import version_from_scm
                import setuptools_scm.git
                describe = (setuptools_scm.git.DEFAULT_DESCRIBE +
                            " --match 'apache-arrow-[0-9]*'")
                # Strip catchall from the commandline
                describe = describe.replace("--match *.*", "")
                version = setuptools_scm.git.parse(root, describe)
                if not version:
                    return version_from_scm(root)
                else:
                    return version
    
            import setuptools_scm
            __version__ = setuptools_scm.get_version('../', parse=parse_version)
        except (ImportError, LookupError):
            __version__ = None
    
    
>   from pyarrow.lib import cpu_count, set_cpu_count
E   ImportError: libboost_regex.so.1.66.0: cannot open shared object file: No such file or directory
/opt/conda/lib/python3.6/site-packages/pyarrow/__init__.py:47: ImportError
During handling of the above exception, another exception occurred:
hdfs = hdfs://localhost:8020, Connected
    @require_pyarrow
    def test_parquet_pyarrow(hdfs):
        dd = pytest.importorskip('dask.dataframe')
        import pandas as pd
        import numpy as np
    
        fn = '%s/test.parquet' % basedir
        hdfs_fn = 'hdfs://%s' % fn
        df = pd.DataFrame(np.random.normal(size=(1000, 4)),
                          columns=list('abcd'))
        ddf = dd.from_pandas(df, npartitions=4)
    
>       ddf.to_parquet(hdfs_fn, engine='pyarrow')
dask/bytes/tests/test_hdfs.py:245: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
dask/dataframe/core.py:1045: in to_parquet
    return to_parquet(self, path, *args, **kwargs)
dask/dataframe/io/parquet.py:892: in to_parquet
    write = get_engine(engine)['write']
dask/dataframe/io/parquet.py:749: in get_engine
    import_required('pyarrow', "`pyarrow` not installed")
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
mod_name = 'pyarrow', error_msg = '`pyarrow` not installed'
    def import_required(mod_name, error_msg):
        """Attempt to import a required dependency.
    
        Raises a RuntimeError if the requested module is not available.
        """
        try:
            return import_module(mod_name)
        except ImportError:
>           raise RuntimeError(error_msg)
E           RuntimeError: `pyarrow` not installed
dask/utils.py:94: RuntimeError
------------------------------ Captured log setup ------------------------------
core.py                    137 DEBUG    Connect to handle 94361929179216
=============== 1 failed, 10 passed, 13 skipped in 11.03 seconds ===============
The command "if [[ $TEST_HDFS == 'true' ]]; then source continuous_integration/hdfs/run_tests.sh; fi" exited with 1.