travis-ci: use 'set -e' in the 32 bit Linux build job

The script 'ci/run-linux32-build.sh' running inside the Docker
container of the 32 bit Linux build job uses an && chain to break the
build if one of the commands fails.  This is problematic for two
reasons:

  - The && chain is broken, because there is this in the middle:

    test -z $HOST_UID || (CI_USER="ci" && useradd -u $HOST_UID $CI_USER) &&

    Luckily it is broken in a way that it didn't lead to false
    successes.  If installing dependencies fails, then the rest of the
    first && chain is skipped and execution resumes  after the ||
    operator.  At that point $HOST_UID is still unset, causing
    'useradd' to error out with "invalid user ID 'ci'", which in turn
    causes the second && chain to abort the script and thus break the
    build.

  - All other 'ci/*' scripts use 'set -e' to break the build if one of
    the commands fails.  This inconsistency among these scripts is
    asking for trouble: I forgot about the && chain more than once
    while working on this patch series.

Enable 'set -e' for the whole script and for the commands executed
under 'su' as well.

While touching every line in the 'su' command block anyway, change
their indentation to use a tab instead of spaces.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ci/run-linux32-build.sh

@@ -6,29 +6,29 @@
 #   run-linux32-build.sh [host-user-id]
 #
 
-set -x
+set -ex
 
 # Update packages to the latest available versions
 linux32 --32bit i386 sh -c '
     apt update >/dev/null &&
     apt install -y build-essential libcurl4-openssl-dev libssl-dev \
 	libexpat-dev gettext python >/dev/null
-' &&
+'
 
 # If this script runs inside a docker container, then all commands are
 # usually executed as root. Consequently, the host user might not be
 # able to access the test output files.
 # If a host user id is given, then create a user "ci" with the host user
 # id to make everything accessible to the host user.
-HOST_UID=$1 &&
-CI_USER=$USER &&
-test -z $HOST_UID || (CI_USER="ci" && useradd -u $HOST_UID $CI_USER) &&
+HOST_UID=$1
+CI_USER=$USER
+test -z $HOST_UID || (CI_USER="ci" && useradd -u $HOST_UID $CI_USER)
 
 # Build and test
 linux32 --32bit i386 su -m -l $CI_USER -c '
-    set -x &&
-    cd /usr/src/git &&
-    ln -s /tmp/travis-cache/.prove t/.prove &&
-    make --jobs=2 &&
+	set -ex
+	cd /usr/src/git
+	ln -s /tmp/travis-cache/.prove t/.prove
+	make --jobs=2
 	make --quiet test
 '