RF: Remove third mask since SyN is currently 2 steps

Author: mgxd

sdcflows/workflows/fit/syn.py

@@ -211,7 +211,7 @@ def init_syn_sdc_wf(
     )
 
     fixed_masks = pe.Node(
-        niu.Merge(3),
+        niu.Merge(2),
         name="fixed_masks",
         mem_gb=DEFAULT_MEMORY_MIN_GB,
         run_without_submitting=True,
@@ -267,13 +267,6 @@ def init_syn_sdc_wf(
     if sloppy:
         bs_filter.inputs.zooms_min = 4.0
 
-    if sd_prior:
-        workflow.connect([
-            (inputnode, atlas_msk, [("sd_prior", "in_file")]),
-            (atlas_msk, fixed_masks, [("out_mask", "in3")]),
-        ])  # fmt:skip
-    else:
-        workflow.connect(inputnode, "anat_mask", fixed_masks, "in3")
 
     workflow.connect([
         (inputnode, readout_time, [(("epi_ref", _pop), "in_file"),