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doc/articles/pitfalls.md

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+<!--
+    tagline: Common mistakes and misconceptions
+-->
+
+# Pitfalls
+
+## I have a dependency which contains a "repositories" definition in its composer.json, but it seems to be ignored.
+
+The [`repositories`](04-schema.md#repositories) configuration property is defined as [root-only]
+(04-schema.md#root-package). It is not inherited. You can read more about the reasons behind this in the "[why can't 
+composer load repositories recursively?](articles/why-can't-composer-load-repositories-recursively.md)" article.
+
+## I have locked a dependency to a specific commit but get unexpected results.
+
+While Composer supports locking dependencies to a specific commit using the `#commit-ref` syntax, there are certain 
+caveats that one should take into account. The most important one is [documented](04-schema.md#package-links), but 
+frequently overlooked:
+
+> **Note:** While this is convenient at times, it should not be how you use
+> packages in the long term because it comes with a technical limitation. The
+> composer.json metadata will still be read from the branch name you specify
+> before the hash. Because of that in some cases it will not be a practical
+> workaround, and you should always try to switch to tagged releases as soon
+> as you can.