copy: add experimetal support for unmarking committed copies The simplest way I'm aware of to unmark a file as copied after committing is this: hg uncommit --keep <dest> hg forget <dest> hg add <dest> hg amend This patch teaches `hg copy --forget` a `-r` argument to simplify that into: hg copy --forget --at-rev . <dest> In addition to being simpler, it doesn't touch the working copy, so it can easily be used even if the destination file has been modified in the working copy. I'll teach `hg copy` without `--forget` to work with `--at-rev` next. Differential Revision: https://phab.mercurial-scm.org/D8030

--- a/relnotes/next	Fri Dec 20 15:50:13 2019 -0800
+++ b/relnotes/next	Tue Jan 28 14:07:57 2020 -0800
@@ -17,6 +17,9 @@
 
 == New Experimental Features ==
 
+ * Use `hg copy --forget --at-rev REV` to unmark already committed
+   copies.
+
 
 == Bug Fixes  ==