Only apply auto-rebuild if something has changed

This will allow us to introduce interrogation commands and avoid
auto-rebuild to kicking in when no modification commands are given.

Signed-off-by: John Keeping <john@keeping.me.uk>
Add '--show' to print the instruction sheet

Signed-off-by: John Keeping <john@keeping.me.uk>
t3001: use '--show' to get the instruction sheet

This is simpler than using a custom editor to extract the instruction
sheet for the integration branch.

Signed-off-by: John Keeping <john@keeping.me.uk>
Suppress SHA-1 from rev-parse during --add

When checking that the ref given to --add is valid, the output of
git-rev-parse is not redirected to /dev/null and appears in the output
stream.  Stop this.

Signed-off-by: John Keeping <john@keeping.me.uk>
Merge branch 'show-command' into pu

* branch show-command:
  t3001: use '--show' to get the instruction sheet
  Add '--show' to print the instruction sheet
  Only apply auto-rebuild if something has changed