sokol-shdc won't compile shader with samplerExternalOES

[oviano]

@vs ext_vs
in vec4 position;
in vec2 texcoord0;
out vec2 uv;

void main()
{
    gl_Position = position;
    uv = texcoord0;
}
@end

/* ext fragment shader */
@fs ext_fs
#extension GL_OES_EGL_image_external : require
uniform samplerExternalOES ext_fs_tex;

in vec2 uv;
out vec4 frag_color;

void main()
{
	frag_color = texture(ext_fs_tex, uv);
}
@end

/* ext shader program */
@program ext ext_vs ext_fs

Two issues:

1. it states it requires GL_OES_EGL_image_external_essl3 even when compiling for glsl100.
2. it cannot find a match for the texture() call.

If I manually embed the shader source below into an sokol app, it works fine. This is what I would have expected sokol-shdc to output. I had a look through the code, and it seems like it ought to work as the version of the glsl code it is using does recognise this extension.

    #version 100
    #extension GL_OES_EGL_image_external : require
    precision mediump float;
    precision highp int;
    
    uniform highp samplerExternalOES ext_fs_tex;
    
    varying highp vec2 uv;
    
    void main()
    {
        gl_FragData[0] = texture2D(ext_fs_tex, uv);
    }