Sagetex ignores indents if they are done in tabs insteads of spaces - how to make it recognize tabs?

Question

The following examples are visually identical code. The only difference is that the indents were done differently. Four spaces were used in the first and a tab was used in the second.

1.

\documentclass{article}
\usepackage{sagetex}
\begin{document}
\begin{sageblock}
def f(x):
    return x
\end{sageblock}
f(x) returns itself.
For example, $f(2)=\sage{f(2)}$.
\end{document}

Output:

 def f(x):
    return x
f(x) returns itself. For example, f(2) = 2.

\documentclass{article}
\usepackage{sagetex}
\begin{document}
\begin{sageblock}
def f(x):
    return x
\end{sageblock}
f(x) returns itself.
For example, $f(2)=\sage{f(2)}$.
\end{document}

Output:

 def f(x):
 return x
f(x) returns itself. For example, f(2) = ??.

Errors:

  File "./example.sagetex.sage.py", line 14
    return x
    ^
IndentationError: expected an indented block
LaTeX Warning: Reference @sageinline0 on page 1 undefined on input line 11.

It is clear that sagetex ignores indents done in tabs by observing the error and how the code is printed verbatim. What can be done so that tabs are also recognized as indents?