update-test: add --to-tag option.

This option is used to test updating between tags.

Library/Homebrew/dev-cmd/update-test.rb

@@ -8,11 +8,16 @@
 #:    If `--before=<date>` is passed, use the commit at `<date>` as the
 #:    start commit.
 #:
+#:    If `--to-tag` is passed, set HOMEBREW_UPDATE_TO_TAG to test updating
+#:    between tags.
+#:
 #:    If `--keep-tmp` is passed, retain the temporary directory containing
 #:    the new repository clone.
 
 module Homebrew
   def update_test
+    ENV["HOMEBREW_UPDATE_TO_TAG"] = "1" if ARGV.include?("--to-tag")
+
     cd HOMEBREW_REPOSITORY
     start_commit = if commit = ARGV.value("commit")
       commit

docs/brew.1.html

@@ -591,6 +591,9 @@ not deleted.</p>
 <p>If <code>--before=&lt;date></code> is passed, use the commit at <code>&lt;date></code> as the
 start commit.</p>
 
+<p>If <code>--to-tag</code> is passed, set HOMEBREW_UPDATE_TO_TAG to test updating
+between tags.</p>
+
 <p>If <code>--keep-tmp</code> is passed, retain the temporary directory containing
 the new repository clone.</p></dd>
 </dl>

manpages/brew-cask.1

 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BREW\-CASK" "1" "September 2016" "Homebrew" "brew-cask"
+.TH "BREW\-CASK" "1" "October 2016" "Homebrew" "brew-cask"
 .
 .SH "NAME"
 \fBbrew\-cask\fR \- a friendly binary installer for macOS

manpages/brew.1

 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BREW" "1" "September 2016" "Homebrew" "brew"
+.TH "BREW" "1" "October 2016" "Homebrew" "brew"
 .
 .SH "NAME"
 \fBbrew\fR \- The missing package manager for macOS
@@ -796,6 +796,9 @@ If \fB\-\-commit=<commit>\fR is passed, use \fB<commit>\fR as the start commit\.
 If \fB\-\-before=<date>\fR is passed, use the commit at \fB<date>\fR as the start commit\.
 .
 .IP
+If \fB\-\-to\-tag\fR is passed, set HOMEBREW_UPDATE_TO_TAG to test updating between tags\.
+.
+.IP
 If \fB\-\-keep\-tmp\fR is passed, retain the temporary directory containing the new repository clone\.
 .
 .SH "EXTERNAL COMMANDS"