Support --import xml.etree.ElementTree in sqlite-utils convert

[simonw]

It's not possible to use a module that requires a nested import, such as xml.etree.ElementTree, at the moment. I found and fixed this bug in git-history, I should replicate that fix (and accompanying documentation) here: simonw/git-history#39

[simonw]

The fix there was:

@@ -463,7 +473,7 @@ def compile_convert(convert, imports):
     locals = {}
     globals = {"json": json}
     for import_ in imports:
-        globals[import_] = __import__(import_)
+        globals[import_.split(".")[0]] = __import__(import_)
     exec(code_o, globals, locals)

With this example (needs to be modified here):

git-history file items.xml --convert '
tree = xml.etree.ElementTree.fromstring(content)
return [el.attrib for el in tree.iter("item")]
' --import xml.etree.ElementTree