Snapcraft could DTRT and ignore .git, .bazaar, .hg folders etc. when source-type is local. It's very unlikely it's needed for the build, and if it is, the developer should probably explicitly say `source-type: $vcs`. A .snapcraftignore file is certainly an option, but would require developer action, and add more snap cruft to the repository. A `source-ignore:` key in the YAML might be more appropriate.