URI redirection issue with upper/lower case traffic

Try this:

when RULE_INIT { 
    set static::asitesext "asites.abc.com" 
    set static::asitesint "asites.internet.abc.com" 
    set static::aportalext "aportal.abc.com" 
    set static::aportalint "aportal.internet.abc.com" 
    set static::amyext "amy.abc.com" 
    set static::amyint "amy.internet.abc.com" 
    set static::aextranetext "aextranet.abc.com" 
    set static::aextranetint "aextranet.internet.abc.com" 
    set static::awww "awww.abc.com" 
} 
when HTTP_REQUEST { 
    if { [class match [IP::client_addr] equals InternalHosts] } {
        log local0. "Redirecting based on InternalHosts match"
        HTTP::redirect http://[HTTP::host][HTTP::uri] 
    } elseif { [class match [string tolower [HTTP::path]] starts_with test] } {
        log local0. "Redirecting based on test match: [HTTP::uri]"
        set origin [class match -name [string tolower [HTTP::path]] starts_with test] 
        set new [class match -value [string tolower [HTTP::path]] starts_with test] 
        set newuri [string map "$origin $new" [string tolower [HTTP::uri]]] 
        HTTP::redirect "https://[HTTP::host]${newuri}" 
        log local0. "New URI = $newuri" 
    } else { 
        log local0. "Replacing the HTTP Host header: [HTTP::host]"
        switch -glob -- [string tolower [HTTP::host]] { 
            "asites.abc.com" { 
                HTTP::header replace Host $static::asitesint 
                STREAM::disable 
            } 
            "awww.abc.com" { 
                HTTP::redirect "https://aportal.abc.com" 
                STREAM::disable 
            } 
            "aportal.abc.com" { 
                HTTP::header replace Host $static::aportalint 
                STREAM::disable 
            } 
            "amy.abc.com" { 
                HTTP::header replace Host $static::amyint 
                STREAM::disable 
            } 
            "aextranet.abc.com" { 
                HTTP::header replace Host $static::aextranetint 
                STREAM::disable 
            } 
        } 
    } 
} 
when HTTP_RESPONSE { 
    if { [HTTP::is_redirect] && [string tolower [HTTP::header "Location"]] contains $static::asitesint } { 
        HTTP::header replace Location [string map "$static::asitesint $static::asitesext" [HTTP::header Location]] 
        STREAM::enable 
    } elseif { [HTTP::is_redirect] && [string tolower [HTTP::header "Location"]] contains $static::aportalint } { 
        HTTP::header replace Location [string map "$static::aportalint $static::aportalext" [HTTP::header Location]] 
        STREAM::enable 
    } elseif { [HTTP::is_redirect] && [string tolower [HTTP::header "Location"]] contains $static::amyint } { 
        HTTP::header replace Location [string map "$static::amyint $static::amyext" [HTTP::header Location]] 
        STREAM::enable 
    } elseif { [HTTP::is_redirect] && [string tolower [HTTP::header "Location"]] contains $static::aextranetint } { 
        HTTP::header replace Location [string map "$static::aextranetint $static::aextranetext" [HTTP::header Location]] 
        STREAM::enable 
    } 
}

Just out of curiosity, do you have a custom STREAM profile defined?