Merge pull request #1272 from blink1073/fix-tifffile-warning

Do not use importlib in `tifffile_local` to avoid warnings

skimage/external/tifffile/tifffile_local.py

@@ -3081,20 +3081,40 @@ def imagej_description(description):
 
 
 def _replace_by(module_function, package=None, warn=False):
-    """Try replace decorated function by module.function."""
-    try:
-        from importlib import import_module
-    except ImportError:
-        warnings.warn('could not import module importlib')
-        return lambda func: func
+    """Try replace decorated function by module.function.
 
+    This is used to replace local functions with functions from another
+    (usually compiled) module, if available.
+
+    Parameters
+    ----------
+    module_function : str
+        Module and function path string (e.g. numpy.ones)
+    package : str, optional
+        The parent package of the module
+    warn : bool, optional
+        Whether to warn when wrapping fails
+
+    Returns
+    -------
+    func : function
+        Wrapped function, hopefully calling a function in another module.
+
+    Example
+    -------
+    >>> @_replace_by('_tifffile.decodepackbits')
+    ... def decodepackbits(encoded):
+    ...     raise NotImplementedError
+
+    """
     def decorate(func, module_function=module_function, warn=warn):
         try:
-            module, function = module_function.split('.')
-            if not package:
-                module = import_module(module)
+            modname, function = module_function.split('.')
+            if package is None:
+                full_name = modname
             else:
-                module = import_module('.' + module, package=package)
+                full_name = package + '.' + modname
+            module = __import__(full_name, romlist=[modname])
             func, oldfunc = getattr(module, function), func
             globals()['__old_' + func.__name__] = oldfunc
         except Exception: