teach init-repository about branches

specifically, add the --branch option and the necessary keys to
.gitmodules.

Change-Id: I09e2df6bd012629f76a35238d66697637bdffe44
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

.gitmodules

@@ -1,139 +1,175 @@
 [submodule "qtbase"]
 	path = qtbase
 	url = ../qtbase.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtsvg"]
 	path = qtsvg
 	url = ../qtsvg.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtdeclarative"]
 	path = qtdeclarative
 	url = ../qtdeclarative.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtactiveqt"]
 	path = qtactiveqt
 	url = ../qtactiveqt.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtscript"]
 	path = qtscript
 	url = ../qtscript.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtmultimedia"]
 	path = qtmultimedia
 	url = ../qtmultimedia.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qttools"]
 	path = qttools
 	url = ../qttools.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtxmlpatterns"]
 	path = qtxmlpatterns
 	url = ../qtxmlpatterns.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qttranslations"]
 	path = qttranslations
 	url = ../qttranslations.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtdoc"]
 	path = qtdoc
 	url = ../qtdoc.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtrepotools"]
 	path = qtrepotools
 	url = ../qtrepotools.git
+	branch = master
 	initrepo = true
 [submodule "qtwebkit"]
 	path = qtwebkit
 	url = ../qtwebkit.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtwebkit-examples"]
 	path = qtwebkit-examples
 	url = ../qtwebkit-examples.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtqa"]
 	path = qtqa
 	url = ../qtqa.git
+	branch = master
 	initrepo = true
 [submodule "qtlocation"]
 	path = qtlocation
 	url = ../qtlocation.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtsensors"]
 	path = qtsensors
 	url = ../qtsensors.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtsystems"]
 	path = qtsystems
 	url = ../qtsystems.git
+	branch = dev
 [submodule "qtfeedback"]
 	path = qtfeedback
 	url = ../qtfeedback.git
+	branch = master
 [submodule "qtdocgallery"]
 	path = qtdocgallery
 	url = ../qtdocgallery.git
+	branch = master
 [submodule "qtpim"]
 	path = qtpim
 	url = ../qtpim.git
+	branch = dev
 [submodule "qtconnectivity"]
 	path = qtconnectivity
 	url = ../qtconnectivity.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtwayland"]
 	path = qtwayland
 	url = ../qtwayland.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qt3d"]
 	path = qt3d
 	url = ../qt3d.git
+	branch = dev
 [submodule "qtimageformats"]
 	path = qtimageformats
 	url = ../qtimageformats.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtquick1"]
 	path = qtquick1
 	url = ../qtquick1.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtgraphicaleffects"]
 	path = qtgraphicaleffects
 	url = ../qtgraphicaleffects.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtquickcontrols"]
 	path = qtquickcontrols
 	url = ../qtquickcontrols.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtserialport"]
 	path = qtserialport
 	url = ../qtserialport.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtx11extras"]
 	path = qtx11extras
 	url = ../qtx11extras.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtmacextras"]
 	path = qtmacextras
 	url = ../qtmacextras.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtwinextras"]
 	path = qtwinextras
 	url = ../qtwinextras.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtandroidextras"]
 	path = qtandroidextras
 	url = ../qtandroidextras.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtenginio"]
 	path = qtenginio
 	url = ../qtenginio.git
+	branch = 1.1.0
 	initrepo = true
 [submodule "qtwebsockets"]
 	path = qtwebsockets
 	url = ../qtwebsockets.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtwebchannel"]
 	path = qtwebchannel
 	url = ../qtwebchannel.git
+	branch = 5.4.0
 	initrepo = true
 [submodule "qtwebengine"]
 	path = qtwebengine
 	url = ../qtwebengine.git
+	branch = 5.4.0
 	initrepo = true

init-repository

@@ -105,6 +105,12 @@ Module names may be prefixed with a dash to exclude them from a bigger set.
 
 Skip the `git submodule update' command.
 
+=item --branch
+
+Instead of checking out specific SHA1s, check out the submodule branches that
+correspond with the current supermodule commit.
+By default, this option will cause local commits in the submodules to be rebased.
+With --no-update, the branches will be checked out, but their heads will not move.
 
 =item --ignore-submodules
 
@@ -233,6 +239,7 @@ sub parse_arguments
 
     %{$self} = (%{$self},
         'alternates'          => "",
+        'branch'              => 0,
         'codereview-username' => "",
         'detach-alternates'   => 0 ,
         'force'               => 0 ,
@@ -246,6 +253,7 @@ sub parse_arguments
 
     GetOptionsFromArray(\@args,
         'alternates=s'      =>  \$self->{qw{ alternates        }},
+        'branch'            =>  \$self->{qw{ branch            }},
         'codereview-username=s' => \$self->{qw{ codereview-username }},
         'copy-objects'      =>  \$self->{qw{ detach-alternates }},
         'force|f'           =>  \$self->{qw{ force             }},
@@ -313,9 +321,10 @@ sub git_submodule_init
 
 sub git_clone_all_submodules
 {
-    my ($self, $my_repo_base, @subset) = @_;
+    my ($self, $my_repo_base, $co_branch, @subset) = @_;
 
     my %subdirs = ();
+    my %subbranches = ();
     my %subbases = ();
     my %subinits = ();
     my @submodconfig = qx(git config -l -f .gitmodules);
@@ -324,6 +333,8 @@ sub git_clone_all_submodules
         next if ($line !~ /^submodule\.([^.=]+)\.([^.=]+)=(.*)$/);
         if ($2 eq "path") {
             $subdirs{$1} = $3;
+        } elsif ($2 eq "branch") {
+            $subbranches{$1} = $3;
         } elsif ($2 eq "url") {
             my ($mod, $base) = ($1, $3);
             next if ($base !~ /^\.\.\//);
@@ -376,16 +387,30 @@ sub git_clone_all_submodules
     }
 
     if ($self->{update}) {
-        $self->exe('git', 'submodule', 'update');
+        $self->exe('git', 'submodule', 'update', ($co_branch ? ('--remote', '--rebase') : ()));
 
         foreach my $module (@modules) {
             if (-f $module.'/.gitmodules') {
                 my $orig_cwd = getcwd();
                 chdir($module) or confess "chdir $module: $OS_ERROR";
-                $self->git_clone_all_submodules($subbases{$module}, "all");
+                $self->git_clone_all_submodules($subbases{$module}, 0, "all");
                 chdir("$orig_cwd") or confess "chdir $orig_cwd: $OS_ERROR";
             }
         }
+    } elsif ($co_branch) {
+        foreach my $module (@modules) {
+            my $branch = $subbranches{$module};
+            die("No branch defined for submodule $module.\n") if (!defined($branch));
+            my $orig_cwd = getcwd();
+            chdir($module) or confess "chdir $module: $OS_ERROR";
+            my $br = qx(git rev-parse -q --verify $branch);
+            if (!$br) {
+                $self->exe('git', 'checkout', '-b', $branch, "origin/$branch");
+            } else {
+                $self->exe('git', 'checkout', $branch);
+            }
+            chdir("$orig_cwd") or confess "chdir $orig_cwd: $OS_ERROR";
+        }
     }
 
     return;
@@ -532,7 +557,7 @@ sub run
     $url =~ s,qt/qt5$,,;
     $self->{'base-url'} = $url;
 
-    $self->git_clone_all_submodules('qt/qt5', @{$self->{'module-subset'}});
+    $self->git_clone_all_submodules('qt/qt5', $self->{branch}, @{$self->{'module-subset'}});
 
     $self->git_add_remotes('qt/qt5');