A function call using a named argument generates an error

[leejt144]

Steps To Reproduce

I am trying to evaluate a definite integral whose upper limit is a variable. Here are the lines,

var('x')
var('x_')

assume(x,'real',x>0)
assume(x_,'real',x_>=0)

f(x) = integrate(1/sqrt(0.3*(1+x_)^3+0.7),x_,0,x)

And then I want to plot f as a function of x,

plot(f(x),(x,0.1,10))

Expected Behavior

I would have expected a 2D plot: x vs. f(x)

Actual Behavior

The plot() call produces the following error message,

verbose 0 (3897: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 200 points.
verbose 0 (3897: plot.py, generate_plot_points) Last error message: 'Substitution using function-call syntax and unnamed arguments has been removed. You can use named arguments instead, like EXPR(x=..., y=...)'

[rburing]

Minimal example of the same bug:

y = 2*hypergeometric([], [], x)
plot(y, (x, 0.1, 1))

Without the multiplication 2* there is no error.