Add RUBY_BUILD_TARBALL_OVERRIDE to override the ruby tarball URL

* Update the check for whether a package is a ruby.

Author: eregon

README.md

@@ -82,9 +82,10 @@ The build process may be configured through the following environment variables:
 | `RUBY_BUILD_CURL_OPTS`          | Additional options to pass to `curl` for downloading.                                            |
 | `RUBY_BUILD_WGET_OPTS`          | Additional options to pass to `wget` for downloading.                                            |
 | `RUBY_BUILD_MIRROR_URL`         | Custom mirror URL root.                                                                          |
-| `RUBY_BUILD_MIRROR_PACKAGE_URL` | Custom complete mirror URL (e.g. http://mirror.example.com/package-1.0.0.tar.gz).                  |
+| `RUBY_BUILD_MIRROR_PACKAGE_URL` | Custom complete mirror URL (e.g. http://mirror.example.com/package-1.0.0.tar.gz).                |
 | `RUBY_BUILD_SKIP_MIRROR`        | Bypass the download mirror and fetch all package files from their original URLs.                 |
 | `RUBY_BUILD_ROOT`               | Custom build definition directory. (Default: `share/ruby-build`)                                 |
+| `RUBY_BUILD_TARBALL_OVERRIDE`   | Custom URL to fetch the ruby tarball from. Overrides the URL in the build definition.            |
 | `RUBY_BUILD_DEFINITIONS`        | Additional paths to search for build definitions. (Colon-separated list)                         |
 | `CC`                            | Path to the C compiler.                                                                          |
 | `RUBY_CFLAGS`                   | Additional `CFLAGS` options (_e.g.,_ to override `-O3`).                                         |

bin/ruby-build

@@ -371,6 +371,10 @@ fetch_tarball() {
   local checksum
   local extracted_dir
 
+  if is_ruby_package "$1" && [ -n "$RUBY_BUILD_TARBALL_OVERRIDE" ]; then
+    package_url="$RUBY_BUILD_TARBALL_OVERRIDE"
+  fi
+
   if [ "$package_url" != "${package_url/\#}" ]; then
     checksum="${package_url#*#}"
     package_url="${package_url%%#*}"
@@ -1203,14 +1207,23 @@ isolated_gem_install() {
 
 apply_ruby_patch() {
   local patchfile
-  case "$1" in
-  ruby-* | jruby-* | rubinius-* | truffleruby-* )
+  if is_ruby_package "$1"; then
     patchfile="$(mktemp "${TMP}/ruby-patch.XXXXXX")"
     cat "${2:--}" >"$patchfile"
 
     local striplevel=0
     grep -q '^--- a/' "$patchfile" && striplevel=1
     patch -p$striplevel --force -i "$patchfile"
+  fi
+}
+
+is_ruby_package() {
+  case "$1" in
+  ruby-* | jruby-* | rubinius-* | truffleruby[+-]* | mruby-* | picoruby-* )
+    return 0
+    ;;
+  *)
+    return 1
     ;;
   esac
 }