chainlint.pl: don't flag broken &&-chain if failure indicated explicitly
There are quite a few tests which print an error messages and then
explicitly signal failure with `false`, `return 1`, or `exit 1` as the
final command in an `if` branch. In these cases, the tests don't bother
maintaining the &&-chain between `echo` and the explicit "test failed"
indicator. Since such constructs are manually signaling failure, their
&&-chain breakage is legitimate and safe -- both for the command
immediately preceding `false`, `return`, or `exit`, as well as for all
preceding commands in the `if` branch. Therefore, stop flagging &&-chain
breakage in these sorts of cases.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>