Drop old bootflag detection, rely on python3-parted

While at it rename "bootflag" into "boot flag" in human readable
strings.

Thanks: Darshaka Pathirana for bug report and debugging
Closes: #19

grml2usb

@@ -184,7 +184,7 @@ parser.add_option(
     "--skip-bootflag",
     dest="skipbootflag",
     action="store_true",
-    help="do not try to check whether the destination has the bootflag set",
+    help="do not try to check whether the destination has the boot flag set",
 )
 parser.add_option(
     "--skip-grub-config",
@@ -512,28 +512,13 @@ def check_boot_flag(device):
         if part is None:
             raise HodorException("parted could not find partition")
         if part.getFlag(parted.PARTITION_BOOT):
-            logging.debug("bootflag is enabled on %s" % device)
+            logging.debug("boot flag is enabled on %s" % device)
             return
-    except HodorException as e:
-        logging.info("%s, falling back to old bootflag detection", e)
     except ImportError:
-        logging.debug("could not import parted, falling back to old bootflag detection")
-
-    with open(boot_dev, "rb") as image:
-        data = image.read(520)
-        bootcode = data[440:]
-        gpt_data = bootcode[70:80]
-
-        if gpt_data == GPT_HEADER:
-            logging.info("GPT detected, skipping bootflag check")
-        elif bootcode[6] == b"\x80":
-            logging.debug("bootflag is enabled")
-        else:
-            logging.debug("bootflag is NOT enabled")
-            raise VerifyException(
-                "Device %s does not have the bootflag set. "
-                "Please enable it to be able to boot." % device
-            )
+        raise VerifyException(
+            "Could not import parted to verify boot flag on %s, please make sure python3-parted is installed."
+            % device
+        )
 
 
 def mkfs_fat16(device):