use a pipe instead of bash process substitution.

When using process substitution, we will not get a shell when typing
ctrl-c. Using a pipe, we need different code for getting the exit code
correct. Therefore we store the task_error value in a file.
This reverts most of 2b8ac09

bin/fai

@@ -335,11 +335,17 @@ unset newhostname
 
 fstart > >( tee -a $LOGDIR/fai.log )  2>&1
 
-task action > >( tee -a $LOGDIR/fai.log ) 2>&1
-
-if [ $task_error -gt 0 -o $? -gt 0 ]; then
+task action |& tee -a $LOGDIR/fai.log
+if [ ${PIPESTATUS[0]} -gt 0 ]; then
     final_exit_code=1
 fi
+if [ -f $LOGDIR/task_error ]; then
+    task_error=$(< $LOGDIR/task_error)
+    if [ $task_error -gt 0 ]; then
+	final_exit_code=1
+    fi
+fi
+
 
 [ -L "/var/run/fai/current_config" ] && rm -f "/var/run/fai/current_config"
 

lib/subroutines

@@ -200,6 +200,7 @@ task_error() {
     task_error_func=${FUNCNAME[*]}
     task_local_error=$1
     [ $1 -gt $task_error ] && task_error=$1
+    echo $1 > $LOGDIR/task_error
     [ $task_error -gt $STOP_ON_ERROR ] && stop_fai_installation
 }
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