1D flame solution save() doesn't appear to overwrite, despite keyword being given

When calling f.save('backup.yaml', name="solution", overwrite=True), the output file does not get overwritten. I may be using this feature incorrectly, but I thought theoverwrite=Truemeant that the contents of the file will be overwritten by the current state of the flame.

Minimal example to showcase the issue is below. backup.yaml should have the contents of the backup_2.yaml. Looking at the mass-flux entry shows that it has the values from backup_1.yaml. The first backup file (backup_1.yaml) is from the starting solution, and backup_2.yaml is the solution in the flame after increasing the boundary mass fluxes and re-calling solve().

I may be using this feature incorrectly and I haven't had time to look at the save() method, but it felt like it might be a bug.

import cantera as ct

p = 101325 # pressure [Pascals]

fuel_inlet_temp= 800.0  # fuel inlet temperature [Kelvin]
oxidizer_inlet_temp= 711.0  # oxidizer inlet temperature [Kelvin]
fuel_mdot= 0.5 # kg/m^2/s
width= 50.0e-3 # Distance between inlets [m]

oxidizer_composition= 'O2:1.0'  # oxidizer composition (right)
fuel_composition= 'H2:1.0'  # fuel composition (left)

# Reaction mechanism
mechanism= 'h2o2.yaml'

gas = ct.Solution(mechanism)

gas.TPY = fuel_inlet_temp, p, oxidizer_composition
density_f = gas.density

gas.TPY = oxidizer_inlet_temp, p, oxidizer_composition
density_o = gas.density

#Unity Lewis number testing
gas.transport_model = 'unity-Lewis-number'

f = ct.CounterflowDiffusionFlame(gas, width=width)

f.set_refine_criteria(ratio=15, slope= 0.15, curve= 0.08, prune= 0.04)
#Set the state of the two inlets
f.fuel_inlet.mdot = fuel_mdot
f.fuel_inlet.X = fuel_composition
f.fuel_inlet.T = fuel_inlet_temp

#Create a guestimate for what the oxidizer mdot would be
f.oxidizer_inlet.mdot = (fuel_mdot / density_f) * density_o*4
f.oxidizer_inlet.X = oxidizer_composition
f.oxidizer_inlet.T = oxidizer_inlet_temp

# Generate initial condition
f.solve(auto=True, loglevel=6)
f.save('backup_1.yaml', name="solution", overwrite=True)
f.save('backup.yaml', name="solution", overwrite=True)

print('mdot info:')
print('Fuel mdot: ' + str(f.fuel_inlet.mdot))
print('Oxidizer mdot: ' + str(f.oxidizer_inlet.mdot))
print('BC State:')
print('Left U: ' + str(f.velocity[0]))
print('Right U: ' + str(f.velocity[-1]))

# Now change the conditions, re-run the flame and overwrite the solution
f.fuel_inlet.mdot = f.fuel_inlet.mdot*2
f.oxidizer_inlet.mdot = f.oxidizer_inlet.mdot*2
f.solve()
f.save('backup_2.yaml', name="solution", overwrite=True)
f.save('backup.yaml', name="solution", overwrite=True)

Cantera / cantera

1D flame solution save() doesn't appear to overwrite, despite keyword being given #1772