scripts: runner: let users copy/paste failed commands

Print a copy/pastable version of any command which fails, to help
debugging.

Signed-off-by: Marti Bolivar <marti@opensourcefoundries.com>
diff --git a/scripts/support/runner/core.py b/scripts/support/runner/core.py
index a38f7b0..8c32cdd 100644
--- a/scripts/support/runner/core.py
+++ b/scripts/support/runner/core.py
@@ -412,7 +412,11 @@
         '''
         if self.debug:
             print(quote_sh_list(cmd))
-        subprocess.check_call(cmd)
+        try:
+            subprocess.check_call(cmd)
+        except subprocess.CalledProcessError:
+            print('Error running {}'.format(quote_sh_list(cmd)))
+            raise
 
     def check_output(self, cmd):
         '''Subclass subprocess.check_output() wrapper.
@@ -423,7 +427,11 @@
         '''
         if self.debug:
             print(quote_sh_list(cmd))
-        return subprocess.check_output(cmd)
+        try:
+            return subprocess.check_output(cmd)
+        except subprocess.CalledProcessError:
+            print('Error running {}'.format(quote_sh_list(cmd)))
+            raise
 
     def popen_ignore_int(self, cmd):
         '''Spawn a child command, ensuring it ignores SIGINT.