binary distribution: relocate text files properly in relative binaries (#13578)

* Make relative binaries relocate text files properly
* rb strings aren't valid in python 2
* move perl to new interface for setup_environment family methods

lib/spack/spack/binary_distribution.py

@@ -521,8 +521,6 @@ def relocate_package(workdir, spec, allow_root):
     old_prefix = str(buildinfo.get('spackprefix',
                                    '/not/in/buildinfo/dictionary'))
     rel = buildinfo.get('relative_rpaths', False)
-    if rel:
-        return
 
     tty.msg("Relocating package from",
             "%s to %s." % (old_path, new_path))

lib/spack/spack/relocate.py

@@ -378,17 +378,21 @@ def replace_prefix_text(path_name, old_dir, new_dir):
     Replace old install prefix with new install prefix
     in text files using utf-8 encoded strings.
     """
-
-    def replace(match):
-        return match.group().replace(old_dir.encode('utf-8'),
-                                     new_dir.encode('utf-8'))
     with open(path_name, 'rb+') as f:
         data = f.read()
         f.seek(0)
-        pat = re.compile(old_dir.encode('utf-8'))
-        if not pat.search(data):
-            return
-        ndata = pat.sub(replace, data)
+        # Replace old_dir with new_dir if it appears at the beginning of a path
+        # Negative lookbehind for a character legal in a path
+        # Then a match group for any characters legal in a compiler flag
+        # Then old_dir
+        # Then characters legal in a path
+        # Ensures we only match the old_dir if it's precedeed by a flag or by
+        # characters not legal in a path, but not if it's preceeded by other
+        # components of a path.
+        old_bytes = old_dir.encode('utf-8')
+        pat = b'(?<![\\w\\-_/])([\\w\\-_]*?)%s([\\w\\-_/]*)' % old_bytes
+        repl = b'\\1%s\\2' % new_dir.encode('utf-8')
+        ndata = re.sub(pat, repl, data)
         f.write(ndata)
         f.truncate()