ENH: anonymize_sid - do sanity check that anonymization script produced output

So it will be for the script to just return original sid if it decides to
not anonymize it, which is to some degree change in behavior.  But I think
it would be beneficial in the long run due to more straight-forward and robust
operation.  Docstring for anon_cmd does not mention that empty output implies
no change in subject id

Author: yarikoptic

heudiconv/utils.py

@@ -110,7 +110,13 @@ def dec(obj):
 
 
 def anonymize_sid(sid, anon_sid_cmd):
-
+    """
+    Raises
+    ------
+    ValueError
+      if script returned an empty string (after whitespace stripping),
+      or output with multiple words/lines.
+    """
     cmd = [anon_sid_cmd, sid]
     shell_return = check_output(cmd)
 
@@ -119,7 +125,14 @@ def anonymize_sid(sid, anon_sid_cmd):
     else:
         anon_sid = shell_return
 
-    return anon_sid.strip()
+    anon_sid = anon_sid.strip()
+    if not anon_sid:
+        raise ValueError(f"{anon_sid_cmd!r} {sid!r} returned empty sid")
+    # rudimentary check for sanity: no multiple lines or words (in general
+    # ok, but not ok for BIDS) in the output
+    if len(anon_sid.split()) > 1:
+        raise ValueError(f"{anon_sid_cmd!r} {sid!r} returned multiline output")
+    return anon_sid
 
 
 def create_file_if_missing(filename, content):