problems with merge in an emacs shell

[Boylan, Ross]

I've followed the instructions in  https://mercurial.selenic.com/wiki/MergingWithEmacs but, when I try to merge, I get
ross at ross-sas:~/PCNG$ hg merge -r244
merging sim-core.sas
*ERROR*: File `'/home/ross/PCNG/sim-core.sas.orig'' does not exist or is not readable
merging sim-core.sas failed!
# many more like that for other files
1 files updated, 0 files merged, 0 files removed, 7 files unresolved

After this, all the named .orig files are in the directory, readable, and apparently identical to the non-orig version.
hg seems to be picking up my configuration file because hg showconfig --debug includes
/home/ross/.hgrc:3: merge-tools.emacsclient.args=--eval "(ediff-merge-with-ancestor \"$local\" \"$other\" \"$base\" nil \"$output\")"
And HGMERGE is set to emacsclient in the shell.

Any ideas what's gone wrong? 

I'm a bit suspicious of the quoting around the file name in the error message, and wonder if a file name with quotes is being searched for.

Thanks.
Ross Boylan 

emacs 24.3.1, hg 2.8.2 on Ubuntu.
https://www.mercurial-scm.org/pipermail/mercurial/2015-August/048597.html for my previous thread on this  topic.This is a different system; I would expect it to have more recent software.