Use remote branch name for local branch if possible.

When setting up a local remote-tracking branch (either on clone or when
the user chooses a different branch in the rc file), kdesrc-build has
preferred a '$remoteName-$branchName' naming convention to try to avoid
stepping on user's existing branches.

In reality most users do not use local branches, and those that do would
(according to feedback I've received) prefer the local and remote branch
names to be the same as per git practice basically everywhere.

Since it's easy enough to check that the local branch doesn't already
exist before creating it, just do that and drop the remote name from the
created branch name.

BUG:294347
FIXED-IN:1.15

kdesrc-build

@@ -70,7 +70,7 @@ use constant {
     KDE_PROJECT_ID   => 'kde-projects',          # git-repository-base for kde_projects.xml
 };
 
-my $versionNum = '1.15-pre2';
+my $versionNum = '1.15-rc1';
 
 # This is a hash since Perl doesn't have a "in" keyword.
 my %ignore_list;  # List of packages to refuse to include in the build list.
@@ -5358,7 +5358,7 @@ sub git_clone_module
             info ("\tSwitching to branch g[$branch]");
             p_chdir($srcdir);
             $result = log_command($module, 'git-checkout',
-                ['git', 'checkout', '-b', "origin-$branch", "origin/$branch"]);
+                ['git', 'checkout', '-b', $branch, "origin/$branch"]);
         }
     }
 
@@ -5435,8 +5435,8 @@ sub git_get_best_remote_names
 # Generates a potential new branch name for the case where we have to setup
 # a new remote-tracking branch for a repository/branch. There are several
 # criteria that go into this:
-# * The name will be in the style $repo-$branch to allow the user to make
-#   $branch-only names.
+# * The local branch name will be equal to the remote branch name to match usual
+#   Git convention.
 # * The name chosen must not already exist. This methods tests for that.
 # * The repo name chosen should be (ideally) a remote name that the user has
 #   added. If not, we'll try to autogenerate a repo name (but not add a
@@ -5462,15 +5462,21 @@ sub git_make_branchname
     my $branch = shift;
     my $chosenName;
 
-    # Pick the first "best" remote name, if available.
-    $chosenName = $remoteNamesRef->[0] if @{$remoteNamesRef};
-    return "$chosenName-$branch" if $chosenName;
-
-    # No name chosen, assume origin.
+    # Use "$branch" directly if not already used, otherwise try
+    # to prefix with the best remote name or origin.
+    my $bestRemoteName = $remoteNamesRef ? $remoteNamesRef->[0] : 'origin';
+    for my $possibleBranch ($branch, "$bestRemoteName-$branch", "origin-$branch") {
+        my @known_branches = eval {
+            # undef == no filter
+            filter_program_output(undef, 'git', 'branch', '--list', $possibleBranch)
+        };
 
-    info (" b[y[*] \tNo existing remote repository found for y[$module], assuming b[g[origin].");
+        # The desired branch name is OK as-is if no exceptions were thrown and
+        # the branch wasn't already known to git.
+        return $possibleBranch if !@known_branches && !$@;
+    }
 
-    return "origin-$branch";
+    croak_runtime("Unable to find good branch name for $module branch name $branch");
 }
 
 # This subroutine finds an existing remote-tracking branch name for the given