Remove atomicfile class.

The interface provided by opener(atomic=True) is inherently unsafe:
if an exception is raised in the code using the atomic file, the
possibly incomplete file will be renamed to its final destination,
defeating the whole purpose of atomic files.

To get around this, we would either need some bad hacks involving
sys.exc_info (to make sure things work in except: blocks), or an
interface to say "file is complete; rename it".

This is the exact interface provided by atomictempfile.  Since there
are no remaining users of the atomicfile class, just remove it.

mercurial/util.py

@@ -1195,24 +1195,7 b' def opener(base, audit=True):'
                 except: pass
                 posixfile.close(self)
 
-    class atomicfile(atomictempfile):
-        """the file will only be copied on close"""
-        def __init__(self, name, mode):
-            self._err = False
-            atomictempfile.__init__(self, name, mode)
-        def write(self, s):
-            try:
-                atomictempfile.write(self, s)
-            except:
-                self._err = True
-                raise
-        def close(self):
-            self.rename()
-        def __del__(self):
-            if not self._err:
-                self.rename()
-
-    def o(path, mode="r", text=False, atomic=False, atomictemp=False):
+    def o(path, mode="r", text=False, atomictemp=False):
         if audit_p:
             audit_path(path)
         f = os.path.join(p, path)
@@ -1228,9 +1211,7 b' def opener(base, audit=True):'
                 d = os.path.dirname(f)
                 if not os.path.isdir(d):
                     os.makedirs(d)
-            if atomic:
-                return atomicfile(f, mode)
-            elif atomictemp:
+            if atomictemp:
                 return atomictempfile(f, mode)
             if nlink > 1:
                 rename(mktempcopy(f), f)