atomictempfile: make close() consistent with other file-like objects. The usual contract is that close() makes your writes permanent, so atomictempfile's use of close() to *discard* writes (and rename() to keep them) is rather unexpected. Thus, change it so close() makes things permanent and add a new discard() method to throw them away. discard() is only used internally, in __del__(), to ensure that writes are discarded when an atomictempfile object goes out of scope. I audited mercurial.*, hgext.*, and ~80 third-party extensions, and found no one using the existing semantics of close() to discard writes, so this should be safe.

--- a/hgext/mq.py	Wed Aug 24 05:42:41 2011 -0400
+++ b/hgext/mq.py	Thu Aug 25 20:21:04 2011 -0400
@@ -1492,7 +1492,7 @@
                 n = repo.commit(message, user, ph.date, match=match,
                                 force=True)
                 # only write patch after a successful commit
-                patchf.rename()
+                patchf.close()
                 self.applied.append(statusentry(n, patchfn))
             except:
                 ctx = repo[cparents[0]]