[FIX] Circular dependency

Closes #1066

Author: oesteban

fmriprep/workflows/bold/base.py

@@ -34,7 +34,6 @@
 from .hmc import init_bold_hmc_wf
 from .stc import init_bold_stc_wf
 from .t2s import init_bold_t2s_wf
-from ..fieldmap import init_sdc_wf
 from .registration import init_bold_reg_wf
 from .resampling import (
     init_bold_surf_wf,
@@ -219,6 +218,7 @@ def init_func_preproc_wf(bold_file, ignore, freesurfer,
         * :py:func:`~fmriprep.workflows.fieldmap.init_nonlinear_sdc_wf`
 
     """
+    from ..fieldmap.base import init_sdc_wf  # Avoid circular dependency (#1066)
 
     ref_file = bold_file
     mem_gb = {'filesize': 1, 'resampled': 1, 'largemem': 1}