CA-263587: extract error content from precheck script

When the precheck script is called directly the output will contain an
XML document on failure. Process it in the same manner as when it
fails during installation of the control package.

Signed-off-by: Simon Rowe <[email protected]>

Author: Simon Rowe

scripts/extensions/pool_update.precheck

@@ -184,10 +184,18 @@ def execute_precheck(session, control_package, yum_conf_file, update_precheck_fi
             raise PrecheckFailure(output)
 
     if os.path.isfile(update_precheck_file):
-        pp = subprocess.Popen(update_precheck_file, shell=False, stdout=subprocess.PIPE, close_fds=True)
+        pp = subprocess.Popen(update_precheck_file, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, close_fds=True)
         precheck_output, _ = pp.communicate()
         xcp.logger.info('pool_update.precheck %r precheck_output=%r', update_precheck_file, precheck_output)
         if pp.returncode != 0:
+            regex = ERROR_XML_START + '.+' + ERROR_XML_END
+            m = re.search(regex, precheck_output, flags=re.DOTALL)
+            if m:
+                try:
+                    xmldoc = xml.dom.minidom.parseString(m.group(0))
+                except:
+                    raise PrecheckFailure(precheck_output)
+                parse_precheck_failure(xmldoc)
             raise PrecheckFailure(precheck_output)
         else:
             if '\n' in precheck_output: