fix(gatsby-dev-cli): Include theme src directories (#22147)

Themes aren't built/compiled like most packages in
the gatsby monorepo so we shouldn't ignore their
src directories.

Author: johno

packages/gatsby-dev-cli/src/__tests__/watch.js

@@ -262,6 +262,9 @@ const monoRepoPackages = [
   `gatsby-source-shopify`,
   `gatsby-source-wikipedia`,
   `gatsby-source-wordpress`,
+  `gatsby-theme-blog`,
+  `gatsby-theme-blog-core`,
+  `gatsby-theme-notes`,
   `gatsby-telemetry`,
   `gatsby-transformer-asciidoc`,
   `gatsby-transformer-csv`,
@@ -312,7 +315,7 @@ jest.mock(`../utils/promisified-spawn`, () => {
   }
 })
 
-describe(`dependency changs`, () => {
+describe(`dependency changes`, () => {
   const { publishPackage } = require(`../local-npm-registry/publish-package`)
   const { installPackages } = require(`../local-npm-registry/install-packages`)
   const { checkDepsChanges } = require(`../utils/check-deps-changes`)

packages/gatsby-dev-cli/src/watch.js

@@ -151,6 +151,10 @@ async function watch(
     return
   }
 
+  const allPackagesIgnoringThemesToWatch = allPackagesToWatch.filter(
+    pkgName => !pkgName.startsWith(`gatsby-theme`)
+  )
+
   const ignored = [
     /[/\\]node_modules[/\\]/i,
     /\.git/i,
@@ -159,7 +163,9 @@ async function watch(
     /[/\\]__mocks__[/\\]/i,
     /\.npmrc/i,
   ].concat(
-    allPackagesToWatch.map(p => new RegExp(`${p}[\\/\\\\]src[\\/\\\\]`, `i`))
+    allPackagesIgnoringThemesToWatch.map(
+      p => new RegExp(`${p}[\\/\\\\]src[\\/\\\\]`, `i`)
+    )
   )
   const watchers = _.uniq(
     allPackagesToWatch