Remove redundant copy of timestamp helper

src/borg/helpers/parseformat.py

@@ -88,26 +88,6 @@ def interval(s):
     return hours
 
 
-def timestamp(s):
-    """Convert a --timestamp=s argument to a datetime object"""
-    try:
-        # is it pointing to a file / directory?
-        ts = safe_s(os.stat(s).st_mtime)
-        return datetime.utcfromtimestamp(ts)
-    except OSError:
-        # didn't work, try parsing as timestamp. UTC, no TZ, no microsecs support.
-        for format in ('%Y-%m-%dT%H:%M:%SZ', '%Y-%m-%dT%H:%M:%S+00:00',
-                       '%Y-%m-%dT%H:%M:%S', '%Y-%m-%d %H:%M:%S',
-                       '%Y-%m-%dT%H:%M', '%Y-%m-%d %H:%M',
-                       '%Y-%m-%d', '%Y-%j',
-                       ):
-            try:
-                return datetime.strptime(s, format)
-            except ValueError:
-                continue
-        raise ValueError
-
-
 def ChunkerParams(s):
     params = s.strip().split(',')
     count = len(params)