Buggy merge of `<runtime>` section

Description

binding-file is generated with bug. For example for the following app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    
    <runtime>
        <gcAllowVeryLargeObjects enabled="true" />
    </runtime>

<runtime><assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  <dependentAssembly>
    <Paket>True</Paket>
    <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-65535.65535.65535.65535" newVersion="12.0.0.0" />
  </dependentAssembly>
</assemblyBinding></runtime>
</configuration>

after command paket install, some useless empty <runtime> section is generated at the end of app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    
    <runtime>
        <gcAllowVeryLargeObjects enabled="true" />
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  <dependentAssembly>
    <Paket>True</Paket>
    <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-65535.65535.65535.65535" newVersion="12.0.0.0" />
  </dependentAssembly>
</assemblyBinding></runtime>

<runtime><assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  
</assemblyBinding></runtime>
</configuration>

Repro steps

Test project attached : PaketTest2.zip

Expected behavior

Do not generate extra empty or do not merge <runtime> sections:

<runtime><assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  
</assemblyBinding></runtime>

Actual behavior

Useless <runtime> section is generated, the section can have different size (number of empty lines inside) depending on some unknown factors.

Known workarounds

Live with it, or remove such empty section after paket install

Reproduce the issue with the attached PaketTest2.zip project by running paket install and comparing its app.config output with the input. Inspect how the runtime and assemblyBinding sections are merged; done means no useless extra empty runtime section is generated.