jenkins.sh: grep in artifact_list only if it exists

It some cases of early build errors, the artifact_list files do not
exist yet, making grep fail.

This is causing trouble where the Jenkins job does not complete until
it times out.
For instance the console ends with:

ERROR (#118): perform_build_steps (Step CHECKOUT failed)
ERROR (#307): build_failure (Build process failed after 1 minutes)
+ jenkins.sh: 1: exit_handler
+ jenkins.sh: exit_handler : 111: true
+ jenkins.sh: exit_handler : 112: upload_to_logserver
+ jenkins.sh: upload_to_logserver : 44: test xdev-01.tcwglab '!=' x
++ jenkins.sh: upload_to_logserver : 45: mktemp -d
+ jenkins.sh: upload_to_logserver : 45: logs_dir=/tmp/tmp.KzE4tbrB88
+ jenkins.sh: upload_to_logserver : 46: sums=
+ jenkins.sh: upload_to_logserver : 49: ssh dev-01.tcwglab mkdir -p '/home/tcwg-buildslave/logs/tcwg-backport-65ff96d8ab4119c637655776aa3df4d3a8131ce5^/0d431ccd6cc23cb1bd5153c6d4ea2c06b039b6c2/x86_64.aarch64-linux-gnu'
+ jenkins.sh: upload_to_logserver : 52: makelog_list=($(read_var ${user_workspace}/build-artifacts.txt 'log_make_[^=]*'))
++ jenkins.sh: upload_to_logserver : 52: read_var /home/tcwg-buildslave/workspace/tcwg-buildfarm/aarch64-linux-gnu/build-artifacts.txt 'log_make_[^=]*'
++ jenkins.sh: read_var : 37: local artifact_list=/home/tcwg-buildslave/workspace/tcwg-buildfarm/aarch64-linux-gnu/build-artifacts.txt
++ jenkins.sh: read_var : 38: local 'var=log_make_[^=]*'
++ jenkins.sh: read_var : 39: grep '^log_make_[^=]*=' /home/tcwg-buildslave/workspace/tcwg-buildfarm/aarch64-linux-gnu/build-artifacts.txt
++ jenkins.sh: read_var : 39: cut -d = -f 2-
grep: /home/tcwg-buildslave/workspace/tcwg-buildfarm/aarch64-linux-gnu/build-artifacts.txt: No such file or directory

and gets stuck here because there is still a background process
waiting for the lock.

This patch is an attempt to avoid that.

Change-Id: I38dff9877bdb6e844bb59859383f1aa0110b1e68

1 files changed, 5 insertions, 1 deletions

diff --git a/jenkins.sh b/jenkins.sh
index d496945e..fa043f2e 100755
--- a/jenkins.sh
+++ b/jenkins.sh
@@ -36,7 +36,11 @@ read_var()
 {
    local artifact_list=$1
    local var=$2
-   grep "^${var}=" "${artifact_list}" | cut -d = -f 2-
+   if [ -f "${artifact_list}" ]; then
+       grep "^${var}=" "${artifact_list}" | cut -d = -f 2-
+   else
+       echo ""
+   fi
 }
 
 upload_to_logserver()