Prefer cwd argument to run_process over chdir. NFC. (#8556)

emcc.py

@@ -455,15 +455,10 @@ def run(args):
     return 0
 
   if '--version' in args:
-    revision = '(unknown revision)'
-    here = os.getcwd()
-    os.chdir(shared.path_from_root())
     try:
-      revision = run_process(['git', 'show'], stdout=PIPE, stderr=PIPE).stdout.split('\n')[0]
+      revision = run_process(['git', 'show'], stdout=PIPE, stderr=PIPE, cwd=shared.path_from_root()).stdout.splitlines()[0]
     except:
-      pass
-    finally:
-      os.chdir(here)
+      revision = '(unknown revision)'
     print('''emcc (Emscripten gcc/clang-like replacement) %s (%s)
 Copyright (C) 2014 the Emscripten authors (see AUTHORS.txt)
 This is free and open source software under the MIT license.
@@ -501,7 +496,7 @@ def run(args):
     with misc_temp_files.get_file(suffix='.o') as temp_target:
       input_file = 'hello_world.c'
       err = run_process([shared.PYTHON, sys.argv[0]] + args + [shared.path_from_root('tests', input_file), '-c', '-o', temp_target], stderr=PIPE, env=debug_env).stderr
-      lines = [x for x in err.split('\n') if shared.CLANG_CC in x and input_file in x]
+      lines = [x for x in err.splitlines() if shared.CLANG_CC in x and input_file in x]
       line = re.search('running: (.*)', lines[0]).group(1)
       parts = shlex.split(line.replace('\\', '\\\\'))
       parts = [x for x in parts if x != '-c' and x != '-o' and input_file not in x and temp_target not in x and '-emit-llvm' not in x]