[Bug?] Problem with git show when not in repository's root dir

Repository structure:

a/         - repository's root dir (.git is in here)
a/a.txt
a/b/b.txt

After merging with conflict:

% git status
a.txt: needs merge
# On branch b1
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#       unmerged:   ../a.txt
#
no changes added to commit (use "git add" and/or "git commit -a")

% git show :1:a.txt
Hello
Good World
Bye

% git show :2:a.txt
Hello
This is where it conflicts
Bye

% cd b

% git status
a.txt: needs merge
# On branch b1
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#       unmerged:   ../a.txt
#
no changes added to commit (use "git add" and/or "git commit -a")

% git show :2:../a.txt    # here's the problem
fatal: ambiguous argument ':2:../a.txt': unknown revision or path not
in the working tree.
Use '--' to separate paths from revisions

Should "git show" be taught with the "--ours" and "--theirs" options?
git checkout knows them, but git show doesn't.  At least to me, "--ours"
and "--theirs" are easier to understand than :1: and :2:

nazri.