tcwg_bmk-build/tcwg_gnu-build: Add traceback printing

The line number you get from the previous
message is confusing. For example:
ERROR at run_step:524

Means that something in the function run_step,
which was called from line 524, called exit.

Instead, add a Python style traceback that
shows the call stack with file, line and the
content of that line.
(though unfortunatley we can't get the line no.
of the exit itself)

Example traceback:
ERROR Traceback (most recent call last):
  File: /tmp/foo.sh, line 37
    foo # hey!
  File: /tmp/foo.sh, line 32
    bar # hi there
  File: /tmp/foo.sh, line 1
    (trap handler, 'exit' call line is unknown)

Change-Id: Id6a2734e2b5ef74d05cd51cdbde9a95e5d5a4b44

1 files changed, 1 insertions, 1 deletions

diff --git a/tcwg_gnu-build.sh b/tcwg_gnu-build.sh
index f88c8e81..24c5c44c 100755
--- a/tcwg_gnu-build.sh
+++ b/tcwg_gnu-build.sh
@@ -64,7 +64,7 @@ verbose2="${verbose2-false}"
 
 if $verbose2; then set -x; fi
 
-trap "eval \"echo ERROR at \${FUNCNAME[0]}:\${BASH_LINENO[0]}\"" EXIT
+trap print_traceback EXIT
 
 # Set start and finish steps for different modes.
 default_start_at=""