patch: teach selectfile about symlinks (issue1438)

tests/test-issue1438

@@ -0,0 +1,16 b''
+#!/bin/sh
+"$TESTDIR/hghave" symlink || exit 80
+
+rm -rf a
+hg init a
+cd a
+
+ln -s foo link
+hg add link
+hg ci -mbad link
+hg rm link
+hg ci -mok
+hg diff -g -r 0:1 > bad.patch
+hg up 0
+hg import --no-commit bad.patch
+hg st

tests/test-issue1438.out

@@ -0,0 +1,4 b''
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+applying bad.patch
+R link
+? bad.patch

mercurial/patch.py

@@ -751,7 +751,7 b' def selectfile(afile_orig, bfile_orig, h'
     nulla = afile_orig == "/dev/null"
     nullb = bfile_orig == "/dev/null"
     abase, afile = pathstrip(afile_orig, strip)
-    gooda = not nulla and os.path.exists(afile)
+    gooda = not nulla and util.lexists(afile)
     bbase, bfile = pathstrip(bfile_orig, strip)
     if afile == bfile:
         goodb = gooda