IIS 7.5 + CGI + SSL - Problems with upload limit? (30MB cap)

I'm hitting a really annoying problem with IIS 7. I've setup my web.config by the books as follows:

<?xml version="1.0" encoding="UTF-8"?><configuration><system.webServer><handlers><add name="Python" path="*.cgi" verb="*" modules="CgiModule" scriptProcessor="C:\Python27\python.exe -u &quot;%s&quot;" resourceType="Unspecified" requireAccess="Script" /></handlers><security><requestFiltering><!-- maxAllowedContentLength is in bytes (B)  --><requestLimits maxAllowedContentLength="1073741824" /> <!-- 1GB --></requestFiltering></security><rewrite><rules><rule name="rewrite to hgwebdir" patternSyntax="Wildcard"><match url="*" /><conditions logicalGrouping="MatchAll" trackAllCaptures="false"><add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" /></conditions><action type="Rewrite" url="hgweb.cgi/{R:1}" /></rule></rules></rewrite></system.webServer><system.web><!-- maxRequestLength is in kilobytes (KB)  --><httpRuntime maxRequestLength="1048576" /> <!-- 1GB --></system.web></configuration>

When I POST to the CGI script (it's hgweb for Mercurial via Python) via HTTP everything is fine - no problems whatsoever.

However, when I POST to the script via HTTPS (SSL) I'm still capped at the default upload limit of 30MB. This doesn't make any sense to me. What is going on?!