Listings with named ranges using pgf's \foreach doesn't work

programas.py

# P1
s = {78, 15, 91, 15}
print len(s)
# FIN P1

# P2
d = {78: 15, 91: 15}
print len(d)
# FIN P2

# P3
n = (17, 3, 1993)
h = (14, 5, 2011)
print n < h
# FIN P3

# P4
x, y = ((27, 3), 9)
z, w = x
print y + w
# FIN P4

# P5
a = 'acabase'
b = set(a)
c = list(b)
c.sort()
print c[2]
# FIN P5

# P6
t = 'papagayo'
w = t.split('a')
print w[3]
# FIN P6

# P7
def f(a, b):
    return a + 2 * b

a = 5
b = 2
print f(b, a)
# FIN P7


# P8
def f(a):
    return x + a

def g(x):
    return x + a

x = 5
a = 7
print f(x) + g(x)
# FIN P8

test.tex

\documentclass{article}
\usepackage{listings}
\usepackage{pgffor}

\usepackage{courier}
\lstset{basicstyle=\ttfamily}
\lstset{language=python}
\lstset{rangeprefix=\#\ } 
\lstset{includerangemarker=false}

\begin{document}

  \foreach \x in {1,2,...,8} { 
    \noindent
    \begin{minipage}[b]{19.8em}
      \lstinputlisting[linerange=P\x-FIN\ P\x]{programas.py}
%     \lstinputlisting[linerange=P1-FIN\ P1]{programas.py}    % This works
      \framebox[18em]{\rule[6ex]{0pt}{0pt}}
      \vspace{0.7em}
    \end{minipage}
  } 

\end{document}