minor #32226 [travis] not all components have a master branch (nicola…

…s-grekas)

This PR was merged into the 3.4 branch.

Discussion
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[travis] not all components have a master branch

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
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b73025a [travis] not all components have a master branch

.github/build-packages.php

@@ -57,7 +57,7 @@
     $versions = @file_get_contents('https://repo.packagist.org/p/'.$package->name.'.json') ?: sprintf('{"packages":{"%s":{"dev-master":%s}}}', $package->name, file_get_contents($dir.'/composer.json'));
     $versions = json_decode($versions)->packages->{$package->name};
 
-    if ($package->version === str_replace('-dev', '.x-dev', $versions->{'dev-master'}->extra->{'branch-alias'}->{'dev-master'})) {
+    if (isset($versions->{'dev-master'}) && $package->version === str_replace('-dev', '.x-dev', $versions->{'dev-master'}->extra->{'branch-alias'}->{'dev-master'})) {
         unset($versions->{'dev-master'});
     }