[rubygems/rubygems] Prefer start_with? and end_with? over regex.

- In one of the cases, filenames were checked for ending with "gz" -
    this is changed to check for ending with ".gz"
  - The change was made to make it even easier to read the code, and to
    match only from the start of the input (as opposed to start of the
    line)

https://github.com/rubygems/rubygems/commit/aac4290271

lib/rubygems/command.rb

@@ -456,7 +456,9 @@ class Gem::Command
     until extra.empty? do
       ex = []
       ex << extra.shift
-      ex << extra.shift if extra.first.to_s =~ /^[^-]/
+      if (!extra.first.to_s.empty? && !extra.first.to_s.start_with?("-"))
+        ex << extra.shift
+      end
       result << ex if handles?(ex)
     end
 

lib/rubygems/remote_fetcher.rb

@@ -252,7 +252,7 @@ class Gem::RemoteFetcher
 
     data = send "fetch_#{uri.scheme}", uri, mtime, head
 
-    if data and !head and uri.to_s =~ /\.gz$/
+    if data and !head and uri.to_s.end_with?(".gz")
       begin
         data = Gem::Util.gunzip data
       rescue Zlib::GzipFile::Error

lib/rubygems/specification.rb

@@ -2104,7 +2104,7 @@ class Gem::Specification < Gem::BasicSpecification
     end
 
     if @specification_version > CURRENT_SPECIFICATION_VERSION and
-      sym.to_s =~ /=$/
+        sym.to_s.end_with?("=")
       warn "ignoring #{sym} loading #{full_name}" if $DEBUG
     else
       super

lib/rubygems/test_utilities.rb

@@ -49,7 +49,7 @@ class Gem::FakeFetcher
 
     path = path.to_s
     @paths << path
-    raise ArgumentError, 'need full URI' unless path =~ %r{^https?://}
+    raise ArgumentError, 'need full URI' unless path.start_with?("https://", "http://")
 
     unless @data.key? path
       raise Gem::RemoteFetcher::FetchError.new("no data for #{path}", path)
@@ -67,7 +67,7 @@ class Gem::FakeFetcher
     if data.respond_to?(:call)
       data.call
     else
-      if path.to_s =~ /gz$/ and not data.nil? and not data.empty?
+      if path.to_s.end_with?(".gz") and not data.nil? and not data.empty?
         data = Gem::Util.gunzip data
       end
       data