BF: Skip downloads that already exist, even if there is no checksum to compare

fsl/add_module/ui.py

@@ -308,7 +308,16 @@ def downloadPlugin(plugin : Plugin, destDir, **kwargs) -> Tuple[str, bool]:
 
     info(f'{plugin.name}...', EMPHASIS)
 
-    if op.exists(destFile) and plugin.checksum is not None:
+    # if file exists, but we don't
+    # have a checksum to verify it,
+    # we assume that it is ok
+    if op.exists(destFile) and plugin.checksum is None:
+        skipDownload = True
+
+    # otherwise we compare checksums,
+    # and re-download the file if they
+    # don't match
+    elif op.exists(destFile) and plugin.checksum is not None:
         info(f'{fname} already exists - calculating SHA256 checksum...')
         destchecksum = calcChecksum(destFile)
         if destchecksum == plugin.checksum:

fsl/scripts/fsl_add_module.py

@@ -133,7 +133,9 @@ def parseArgs(argv : List[str]) -> argparse.Namespace:
     }
 
     parser = argparse.ArgumentParser(
-        'fsl_add_module', 'Download and install FSL plugins')
+        'fsl_add_module',
+        usage='fsl_add_module [options] [plugins]',
+        description='Download and install FSL plugins')
     parser.add_argument(
         '-V', '--version', action='version', help=helps['version'],
         version='%(prog)s {}'.format(__VERSION__))