sync: Fix git command for aborting rebase being called incorrectly.

The argument list was incorrectly destructured so only the first
element of the list was considered a git-cmd, split up by each
character in the string.

Change-Id: Idee8a95a89a7da8b8addde07135354fc506c2758
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/435839


Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Erik Elmeke <erik@haleytek.corp-partner.google.com>
Tested-by: Erik Elmeke <erik@haleytek.corp-partner.google.com>