You're feeding an invalid URL to LWP, so unexpected results are to be expected. I bet it works fine when you provide a valid URL. 

use Encode      qw( encode decode );
use URI::Escape qw( uri_escape );

# From DB
my $title = decode('UTF-8', "OverlordQ/R\x{C4}\x{AB}ga-Herson-Astrahan
+");

# Escape each URL component.
my @uri_components = map { uri_escape(encode('UTF-8', $_)) }
                     split qr{/},
                     $title;

# Prints OverlordQ/R%C4%ABga-Herson-Astrahan
print(join('/', @uri_components), "\n");

[download]

uri_escape(encode('UTF-8', $_)) can be written as uri_escape_utf8($_)

Original content of the parent

Alright, in my Perl codings, I've done some work with respect to Wikipedia. One thing you'll find on Wikipedia is plenty of Unicode. Now unfortunately, I've come across some snags when trying to do some work. Since I'm not conversant with all the Black Magic(tm) with Character Encodings when I mention Unicode, I likely mean the UTF8 encoding of it.

Lets establish some facts:

  1. Titles can be Unicode strings
  2. Example title is: Rīga-Herson-Astrahan
  3. This (should) escaped to: R%C4%ABga-Herson-Astrahan
  4. When (not) marked as UTF8, it decodes correctly
  5. When marked as UTF8, it decodes incorrectly

Stepping through the code I have provided below, you eventually to URI at line 77: 

  DB<18> x $str
0  'http://en.wikipedia.org/w/api.php?prop=revisions&format=xml&titles
+=User:OverlordQ/R&#299;ga-Herson-Astrahan&action=query&rvlimit=20'

[download]
The first run through the regex, it eats a character: 
  DB<20> p $1
▒
  DB<21> x unpack("U*",$1);
0  196
Odd, oh well, let us let the regex finish until we get to line 78. Now lets see what the url contains: 
  DB<24> x $str
0  'http://en.wikipedia.org/w/api.php?prop=revisions&format=xml&titles
+=User:OverlordQ/R%C3%84%C2%ABga-Herson-Astrahan&action=query&rvlimit=
+20'

[download]
Hurm, not fun, that's not what we should have got. Bug? Or should I not be telling perl that these strings may contain utf8 characters. Example below. (It abuses the pre tag since the code tag eats the characters) 
#!/usr/bin/perl
use strict;
use warnings;
use lib '/home/overlordq/lib';
use LWP::UserAgent;
use Data::Dumper;
use DBI;
use wikidb;

$|++;

my $ua = LWP::UserAgent->new();

my $dbh = DBI->connect("DBI:mysql:database=enwiki_p;host=sql-s1",$user
+,$password);
my $query = "SELECT page_title FROM page WHERE page_title LIKE 'Overlo
+rdQ%' AND page_id = '22325873'";
my $sth = $dbh->prepare($query);
$sth->execute();
my $title;
while(my $ref = $sth->fetchrow_hashref() ) {
        $title = $ref->{'page_title'};
}

print "Title: $title\n";
if( isUTF($title) ) {
        print "\tis UTF8\n";
} else {
        print "\tis not UTF8\n";
}

my $res = $ua->post('http://en.wikipedia.org/w/api.php?prop=revisions&
+format=xml&titles=User:' . $title . '&action=query&rvlimit=20');

my $uriUsed = $res->request->uri->as_string;

print "URI: $uriUsed\n";

if( isUTF($title) ) {
        print "\tis already UTF8\n";
} else {
        utf8::upgrade($title);
        if( isUTF($title) ) {

                print "$title\n\tis now UTF8\n";
        }
}

$res = $ua->post('http://en.wikipedia.org/w/api.php?prop=revisions&for
+mat=xml&titles=User:' . $title . '&action=query&rvlimit=20');

$uriUsed = $res->request->uri->as_string;

print "URI: $uriUsed\n";


print "Title: $title\n";

sub isUTF {
        my $string = shift;
        return utf8::is_utf8($string);
}

[download]
Output: 
Title: OverlordQ/Rīga-Herson-Astrahan
        is not UTF8
URI: http://...?...&titles=User:OverlordQ/R%C4%ABga-Herson-Astrahan&...
OverlordQ/Rīga-Herson-Astrahan
        is now UTF8
URI: http://...?...&titles=User:OverlordQ/R%C3%84%C2%ABga-Herson-Astrahan&...
Title: OverlordQ/Rīga-Herson-Astrahan

Update: Shortened URLs in PRE tags as per reply.

In reply to Re: URIs and UTF8 by ikegami
in thread URIs and UTF8 by OverlordQ

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
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