diff --git a/src/Composer/Autoload/ClassLoader.php b/src/Composer/Autoload/ClassLoader.php
index 4626994fd..2c72175e7 100644
--- a/src/Composer/Autoload/ClassLoader.php
+++ b/src/Composer/Autoload/ClassLoader.php
@@ -374,9 +374,13 @@ class ClassLoader
 
         $first = $class[0];
         if (isset($this->prefixLengthsPsr4[$first])) {
-            foreach ($this->prefixLengthsPsr4[$first] as $prefix => $length) {
-                if (0 === strpos($class, $prefix)) {
-                    foreach ($this->prefixDirsPsr4[$prefix] as $dir) {
+            $subPath = $class;
+            while (false !== $lastPos = strrpos($subPath, '\\')) {
+                $subPath = substr($subPath, 0, $lastPos);
+                $search = $subPath.'\\';
+                if (isset($this->prefixDirsPsr4[$search])) {
+                    foreach ($this->prefixDirsPsr4[$search] as $dir) {
+                        $length = $this->prefixLengthsPsr4[$first][$search];
                         if (file_exists($file = $dir . DIRECTORY_SEPARATOR . substr($logicalPathPsr4, $length))) {
                             return $file;
                         }
diff --git a/src/Composer/Downloader/PathDownloader.php b/src/Composer/Downloader/PathDownloader.php
index cde32f4a6..79b687985 100644
--- a/src/Composer/Downloader/PathDownloader.php
+++ b/src/Composer/Downloader/PathDownloader.php
@@ -46,6 +46,10 @@ class PathDownloader extends FileDownloader implements VcsCapableDownloaderInter
         }
 
         if (strpos(realpath($path) . DIRECTORY_SEPARATOR, $realUrl . DIRECTORY_SEPARATOR) === 0) {
+            // IMPORTANT NOTICE: If you wish to change this, don't. You are wasting your time and ours.
+            //
+            // Please see https://github.com/composer/composer/pull/5974 and https://github.com/composer/composer/pull/6174
+            // for previous attempts that were shut down because they did not work well enough or introduced too many risks.
             throw new \RuntimeException(sprintf(
                 'Package %s cannot install to "%s" inside its source at "%s"',
                 $package->getName(), realpath($path), $realUrl
diff --git a/src/Composer/Repository/Vcs/SvnDriver.php b/src/Composer/Repository/Vcs/SvnDriver.php
index f2d6a4754..ffc7183f7 100644
--- a/src/Composer/Repository/Vcs/SvnDriver.php
+++ b/src/Composer/Repository/Vcs/SvnDriver.php
@@ -301,12 +301,20 @@ class SvnDriver extends VcsDriver
             return true;
         }
 
+        // Subversion client 1.7 and older
         if (false !== stripos($processExecutor->getErrorOutput(), 'authorization failed:')) {
             // This is likely a remote Subversion repository that requires
             // authentication. We will handle actual authentication later.
             return true;
         }
 
+        // Subversion client 1.8 and newer
+        if (false !== stripos($processExecutor->getErrorOutput(), 'Authentication failed')) {
+            // This is likely a remote Subversion or newer repository that requires
+            // authentication. We will handle actual authentication later.
+            return true;
+        }
+
         return false;
     }