Using the `auto_name` values will result in cache misses when caching is based
on the generated source code, so we're not going to use it.

This should prevent errors when the input is already a Numba scalar, and it
will use Numba's type information to selectively apply the scalar conversion.

Closes #1220

* Also fixes bug in JITCompiler when first output of inner fgraph is an input variable, as can happen in some specific functions with updates

Otherwise TestSharedOptions.test_specify_shape_inplace would fail