Emacs (Aquamacs) VC (SVN) failure to authenticate

At somepoint when I upgraded my Aquamacs this stopped working:
C-x v v  within aquamacs should do an "svn commit".

svn: E215004: Authentication failed and interactive prompting is disabled; see the --force-interactive option
svn: E215004: Commit failed (details follow):
svn: E215004: Unable to connect to a repository at URL 'https://svn.foo.com/svn/myproject/etc/etc'
svn: E215004: No more credentials or we tried too many times.
Authentication failed

Aquamacs version:
GNU Emacs 23.4.1 (x86_64-apple-darwin12.3.0, NS apple-appkit-1187.37) of 2013-06-13 on acs-trailblazer.ist.psu.edu - Aquamacs Distribution 2.5

from cmd-line, same thing!  I thought that worked.

GNU Emacs 24.3.1 (x86_64-apple-darwin12.5.0) of 2013-12-22 on teneight-slave.macports.org

there is the possibility something in my .emacs

no; 'emacs -q' produces the same thing.

vc.el ?  I guess next step is to load the elisp source, and start to dig in.

For now, I've reverted to calling svn from the cmd line.

I'm trying to switch over to git anyway, and this just encourages that (because vc+git is (still) working)...

Mercurial error-- hg ... "abort: cannot follow nonexistent file: "

There is a simple solution near the end..

I don't know much about Mercurial, except that it's a free revision control system and included with NetBeans. I was playing with the GUI builder and didn't want to pollute a subversion-controlled project, but did want to be able to revert back if necessary, and somewhere saw that Mercurial didn't need a server.

Anyway, it was working fine, then I went away from my work for a week or so,
had some more stuff that needed to be checked in before I could test moving part of a module to another project.

.. but on trying to commit my changes in NetBeans, I got an error dialog with instructions to see the output window, which contained the arguments to hg plus the message
abort: cannot follow nonexistent file: src/com/foo/frop/ickyGui.java
followed by one of the project files I was trying to check in.

I knew hg put its stuff in a tree somewhere, found it in NetBeansProjects/MyProject/.hg.
There is a file here for every src file in my project (filenames minorly encoded), plus a couple metadata files per directory. When I looked for the file hg complained about, it wasn't there.
Yet hg though it was checked in. How to convince it otherwise?

I didn't see any commands in the menus that looked promising,
google's first page of results were just statements that 'Mercurial is unfriendly'.
I really didn't want to spend a lot of time on this. Worst case I could create a new project and check it all in again. But I know how to mess with things which is generally the first step in reverse-engineering, so..

SOLUTION
I moved the files out of the way,
and then Mercurial said they were gone.
I committed this change.
I moved the files back,
Mercurial said they were new.
I added them.

And I remembered something I might have done--I restored a MacBook from TimeMachine backup as a way to migrate to another machine. Possibly that Mercurial file was one of the last, or somehow that file feel in the cracks one of the times I aborted backups.

Ideally, hg or netbeans would provide some graceful recovery.