test-convert-git: Use ~ instead of ^
Solaris sh interprets ^ as pipe symbol and the test thus failed in strange
ways. git can however use of HEAD~ instead of HEAD^.
% no diff if hardlink
% init
adding foo to series file
applying foo
now at: foo
adding bar to series file
applying bar
now at: bar
430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c:bar
%
foo
bar
%%%
430ed4828a74fa4047bc816a25500f7472ab4bfe:foo
%
foo
patch foo finalized without changeset message
patch bar finalized without changeset message
%%%
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
430ed4828a74fa4047bc816a25500f7472ab4bfe bar
%
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo
430ed4828a74fa4047bc816a25500f7472ab4bfe lbar
%%%
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo
%
4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo