Fix typos: s/the the/the/

doc/manual/command-ref/nix-env.xml

@@ -416,7 +416,7 @@ $ nix-env --install gcc-3.3.2
 installing `gcc-3.3.2'
 uninstalling `gcc-3.1'</screen>
 
-Note the the previously installed version is removed, since
+Note the previously installed version is removed, since
 <option>--preserve-installed</option> was not specified.</para>
 
 <para>To install an arbitrary version:

doc/manual/introduction/about-nix.xml

@@ -197,7 +197,7 @@ collection</emphasis> (Nixpkgs).</para>
 <simplesect><title>Managing build environments</title>
 
 <para>Nix is extremely useful for developers as it makes it easy to
-automatically set up the the build environment for a package. Given a
+automatically set up the build environment for a package. Given a
 Nix expression that describes the dependencies of your package, the
 command <command>nix-shell</command> will build or download those
 dependencies if they’re not already in your Nix store, and then start

src/libexpr/primops.cc

@@ -1213,7 +1213,7 @@ static void prim_head(EvalState & state, const Pos & pos, Value * * args, Value
 }
 
 
-/* Return a list consisting of everything but the the first element of
+/* Return a list consisting of everything but the first element of
    a list.  Warning: this function takes O(n) time, so you probably
    don't want to use it!  */
 static void prim_tail(EvalState & state, const Pos & pos, Value * * args, Value & v)

src/libstore/gc.cc

@@ -96,7 +96,7 @@ Path addPermRoot(StoreAPI & store, const Path & _storePath,
                 "(are you running nix-build inside the store?)") % gcRoot);
 
     if (indirect) {
-        /* Don't clobber the the link if it already exists and doesn't
+        /* Don't clobber the link if it already exists and doesn't
            point to the Nix store. */
         if (pathExists(gcRoot) && (!isLink(gcRoot) || !isInStore(readLink(gcRoot))))
             throw Error(format("cannot create symlink ‘%1%’; already exists") % gcRoot);