Changes

RenameDetector: Clarify rename limits <= 0

Change-Id: I8da386e02272316b8e5e5c2f31ce10ad98bcdb28

Fix null return from FS.readPipe when command fails to launch

When a command invoked from readPipe fails to launch (i.e. the exec call
fails due to a missing command executable), Process.start() throws,
which gets caught by the generic IOException handler, resulting in a
null return. This change detects this case and rethrows a
CommandFailedException instead.

Additionally, this change uses /bin/sh instead of bash for its posix
command failure test, to accomodate building in environments where bash
is unavailable.

Change-Id: Ifae51e457e5718be610c0a0914b18fe35ea7b008
Signed-off-by: Bryan Donlan <bdonlan@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Fix out-of-bounds exception in RepoCommand#relative

Change-Id: I9c91aa2ff037bff27a8131fba54be22f5f27d80d
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>