rf(CommandError): discontinue to_str() method

In a previous implementation this method used to have parameters, but
presently it does not. Nevertheless it represented a public API
components without a real purpose. it was removed and the same
functionality continues to be available via the standard `__str__()`
method.

datasalad/runners/exception.py

@@ -41,7 +41,7 @@ def __init__(
         self.stderr = stderr
         self.cwd = cwd
 
-    def to_str(self) -> str:
+    def __str__(self) -> str:
         # we report the command verbatim, in exactly the form that it has
         # been given to the exception. Previously implementation have
         # beautified output by joining list-format commands with shell
@@ -67,12 +67,8 @@ def to_str(self) -> str:
             # but we support it, because CommandError derives
             # from RuntimeError which has this feature.
             to_str += f" [{self.msg}]"
-
         return to_str
 
-    def __str__(self) -> str:
-        return self.to_str()
-
     def __repr__(self) -> str:
         descr = f"{self.__class__.__name__}({self.cmd!r}"
         for kwarg, (val, default) in dict(

datasalad/runners/tests/test_exception.py

@@ -51,5 +51,5 @@ def test_CommandError_str_repr() -> None:
              "CommandError('mycmd', returncode=-6)")
         )
     for ce, _str, _repr in testcases:
-        assert ce.to_str() == str(ce) == _str
+        assert str(ce) == _str
         assert repr(ce) == _repr