Simplify repo helper in GitSpecHelpers
Simplify repo helper in GitSpecHelpers

Condense two separate calls to `Dir.chdir(path)` into a single call with
a block passed in.

Change-Id: I41b089981414d4f02757740e411f336d5e18102a
Reviewed-on: https://gerrit.causes.com/25222
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@causes.com>
Reviewed-by: Shane da Silva <6f6e68d1df92f30cb4b3ce35260ddf94a402f33d@causes.com>

blech75/overcommit,gnagel/overcommit,blech75/overcommit,oxocode/overcommit,TheSooth/overcommit,oxocode/overcommit,gnagel/overcommit,TheSooth/overcommit