Merge pull request #291 from CocoaPods/seg-dependency-from-string-head

[Dependency] Allow creating from a string that has HEAD info

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 ## Master
 
+##### Enhancements
+
+* Dependencies created from a string that use the `HEAD` specifier are properly
+  parsed, ignoring the obsolete specifier.  
+  [Samuel Giddins](https://github.com/segiddins)
+  [CocoaPods#4710](https://github.com/CocoaPods/CocoaPods/issues/4710)
+
 ##### Bug Fixes
 
 * Fix specifying `configuration(s)` for a pod inside a target block.   

lib/cocoapods-core/dependency.rb

@@ -340,6 +340,8 @@ def to_s
     #           part by clients that need to create a dependency equal to the
     #           original one.
     #
+    # @todo     Remove the `HEAD` code once everyone has migrated past 1.0.
+    #
     # @return   [Dependency] the dependency described by the string.
     #
     def self.from_string(string)
@@ -348,6 +350,9 @@ def self.from_string(string)
       version = match_data[2]
       version = version.gsub(/[()]/, '') if version
       case version
+      when ' HEAD'
+        CoreUI.warn "Ignoring obsolete `HEAD` specifier in `#{string}`"
+        Dependency.new(name)
       when nil, /from `(.*)(`|')/
         Dependency.new(name)
       else