Fix opening/viewings PRs from the branch pages on the srcfpo theme
    
    The fix here was already applied to the default templates in two commits:
    afc268a69975830c6e54d886e93350fe90639d16 and
    abeec3ae623ad5f15624cac6407669fa9e1fa11b
    
    This commit just port them to the srcfpo theme so they also work there.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>