BUG: merge -s theirs is not in effect (does the same as -s ours)

My interest was to get remote branch "merge" the changes in the branch taking the branch's version (primarily alternative symlinks for git-annex'ed content) over the version in master (previous merge of a similar branch). Unfortunately -s theirs seems to do actually -s ours -- symlinks and content is taken from the 'ours' branch instead of theirs. workaround -- perform -s ours of master within the branch, and then ff of master to that state:

$> git --version git version 2.14.1.729.g59c0ea183a

$> rm -rf /tmp/repo1; mkdir /tmp/repo1; cd /tmp/repo1; git init .; ln -s sym1 link; echo 1 > file; git add file link; git commit -m 'common'; git co -b b1 ; ln -sf b1link link; echo "b1 file" >| file; git commit -m 'b2 changes' -a; git co master; ln -sf masterlink link; echo "master file" >| file; git commit -m 'also modified in master' -a; git merge -s theirs --no-edit b1; ls -l link; cat file
E: could not determine git repository root
warning: templates not found /home/yoh/share/git-core/templates
Initialized empty Git repository in /tmp/repo1/.git/
[master (root-commit) b6a69d0] common
 2 files changed, 2 insertions(+)
 create mode 100644 file
 create mode 120000 link
Switched to a new branch 'b1'
[b1 739eb85] b2 changes
 2 files changed, 2 insertions(+), 2 deletions(-)
Switched to branch 'master'
[master 18a2da4] also modified in master
 2 files changed, 2 insertions(+), 2 deletions(-)
args: b6a69d0c0c2500530cba8bc2987a1f79998b5e74 -- HEAD 739eb853c480b729ec07da533610243e3a6d69ee
Merge made by the 'theirs' strategy.
lrwxrwxrwx 1 yoh yoh 10 Sep 24 19:58 link -> masterlink
master file