fix #7165, leave more tabs alone in triple-quoted strings

Author: JeffBezanson

base/string.jl

@@ -963,6 +963,7 @@ function indentation(s::String)
 end
 
 function unindent(s::String, indent::Int)
+    indent == 0 && return s
     buf = IOBuffer(Array(Uint8,endof(s)), true, true)
     truncate(buf,0)
     a = i = start(s)
@@ -973,7 +974,9 @@ function unindent(s::String, indent::Int)
         if cutting && isblank(c)
             a = i_
             cut += blank_width(c)
-            if cut > indent
+            if cut == indent
+                cutting = false
+            elseif cut > indent
                 cutting = false
                 for _ = (indent+1):cut write(buf, ' ') end
             end

test/strings.jl

@@ -806,6 +806,23 @@ s = "   p"
 @test """
        $s
       """ == " $s$(nl)"
+@test """\t""" == "\t"
+@test """
+      \t""" == ""
+@test """
+      foo
+      \tbar""" == "foo\n\tbar"
+@test """
+      foo
+      \tbar
+      """ == "foo\n\tbar\n"
+@test """
+      foo
+      bar\t""" == "foo\nbar\t"
+@test """
+      foo
+      \tbar
+       """ == "foo\n       bar\n"
 
 # bytes2hex and hex2bytes
 hex_str = "d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592"