Fix incorrect cache reference in --exact mode (#547)

When we prepend a single quote to our query in --exact mode, we are not
supposed to limit the scope of the new search to the previous
exact-match result.

src/pattern.go

@@ -227,7 +227,7 @@ func (p *Pattern) CacheKey() string {
 	}
 	cacheableTerms := []string{}
 	for _, termSet := range p.termSets {
-		if len(termSet) == 1 && !termSet[0].inv {
+		if len(termSet) == 1 && !termSet[0].inv && (p.fuzzy || termSet[0].typ == termExact) {
 			cacheableTerms = append(cacheableTerms, string(termSet[0].origText))
 		}
 	}

test/test_go.rb

@@ -1157,6 +1157,16 @@ class TestGoFZF < TestBase
     end
   end
 
+  def test_partial_caching
+    tmux.send_keys 'seq 1000 | fzf -e', :Enter
+    tmux.until { |lines| lines[-2] == '  1000/1000' }
+    tmux.send_keys 11
+    tmux.until { |lines| lines[-2] == '  19/1000' }
+    tmux.send_keys 'C-a', "'"
+    tmux.until { |lines| lines[-2] == '  28/1000' }
+    tmux.send_keys :Enter
+  end
+
 private
   def writelines path, lines
     File.unlink path while File.exists? path