Unify and use Git username/email/GPG handling.

We're using essentially the same logic to setup Git for committing in
multiple places but the way we're doing so is inconsistent. Moved to
using two shared utility methods and use them consistently.

Library/Homebrew/dev-cmd/bottle.rb

@@ -549,6 +549,7 @@ module Homebrew
 
         unless args.no_commit?
           Utils::Git.set_name_email!
+          Utils::Git.setup_gpg!
 
           short_name = formula_name.split("/", -1).last
           pkg_version = bottle_hash["formula"]["pkg_version"]

Library/Homebrew/dev-cmd/pr-pull.rb

@@ -64,27 +64,6 @@ module Homebrew
     end
   end
 
-  def setup_git_environment!
-    # Passthrough Git environment variables
-    ENV["GIT_COMMITTER_NAME"] = ENV["HOMEBREW_GIT_NAME"] if ENV["HOMEBREW_GIT_NAME"]
-    ENV["GIT_COMMITTER_EMAIL"] = ENV["HOMEBREW_GIT_EMAIL"] if ENV["HOMEBREW_GIT_EMAIL"]
-
-    # Depending on user configuration, git may try to invoke gpg.
-    return unless Utils.popen_read("git config --get --bool commit.gpgsign").chomp == "true"
-
-    begin
-      gnupg = Formula["gnupg"]
-    rescue FormulaUnavailableError
-      nil
-    else
-      if gnupg.any_version_installed?
-        path = PATH.new(ENV.fetch("PATH"))
-        path.prepend(gnupg.any_installed_prefix/"bin")
-        ENV["PATH"] = path
-      end
-    end
-  end
-
   # Separates a commit message into subject, body, and trailers.
   def separate_commit_message(message)
     subject = message.lines.first.strip
@@ -375,7 +354,8 @@ module Homebrew
     mirror_repo = args.bintray_mirror || "mirror"
     tap = Tap.fetch(args.tap || CoreTap.instance.name)
 
-    setup_git_environment!
+    Utils::Git.set_name_email!
+    Utils::Git.setup_gpg!
 
     args.named.uniq.each do |arg|
       arg = "#{tap.default_remote}/pull/#{arg}" if arg.to_i.positive?

Library/Homebrew/dev-cmd/vendor-gems.rb

@@ -35,10 +35,8 @@ module Homebrew
       ohai "git add vendor/bundle"
       system "git", "add", "vendor/bundle"
 
-      if Formula["gpg"].optlinked?
-        ENV["PATH"] = PATH.new(ENV["PATH"])
-                          .prepend(Formula["gpg"].opt_bin)
-      end
+      Utils::Git.set_name_email!
+      Utils::Git.setup_gpg!
 
       ohai "git commit"
       system "git", "commit", "--message", "brew vendor-gems: commit updates."

Library/Homebrew/utils/git.rb

@@ -126,6 +126,13 @@ module Utils
       ENV["GIT_COMMITTER_EMAIL"] = Homebrew::EnvConfig.git_email if committer
     end
 
+    def setup_gpg!
+      return unless Formula["gnupg"].optlinked?
+
+      ENV["PATH"] = PATH.new(ENV["PATH"])
+                        .prepend(Formula["gnupg"].opt_bin)
+    end
+
     def origin_branch(repo)
       Utils.popen_read(git, "-C", repo, "symbolic-ref", "-q", "--short",
                        "refs/remotes/origin/HEAD").chomp.presence