install: Less output on success; once on failure

This fixes 2 aspects of `pip install output`:

1. When `pip install` succeeds, it's still printing a lot of output from
   the package's setup.py. The average consumer of Python packages, when
   they do `pip install lxml`, probably doesn't care to see a bunch of
   output about:

   - copying files to a `build` directory
   - installing and running Cython
   - compiling C code

   This is noise to most when the `pip install` succeeds. It's useful to
   see all the output when the install fails, which is the subject of pypa#2
   below. On success, the output is now very clean with 5 short lines:

       $ pip install lxml
       Collecting lxml
         Using cached lxml-3.4.2.tar.gz
       Installing collected packages: lxml
         Running setup.py install for lxml
       Successfully installed lxml-3.4.2

2. When there's an error from `pip install`, it's annoying to have to
   scroll through 2 different copies of the failure output (especially when
   one is filtered and one is unfiltered so one might have stuff that the
   other doesn't). This makes it not print the filtered version so that
   there is just the unfiltered version and nothing is repeated.

       $ pip install ~/dev/git-repos/lxml
       Processing /Users/marca/dev/git-repos/lxml
       Installing collected packages: lxml
         Running setup.py install for lxml
           Complete output from command ...
           cc -c /var/folders/gw/w0clrs515zx9x_55zgtpv4mm0000gp/T/xmlCheckVersion4tBaVV.c -o var/folders/gw/w0clrs515zx9x_55zgtpv4mm0000gp/T/xmlCheckVersion4tBaVV.o
           /var/folders/gw/w0clrs515zx9x_55zgtpv4mm0000gp/T/xmlCheckVersion4tBaVV.c:1:10: fatal error: 'libxml/xmlversion.h' file not found
           #include "libxml/xmlversion.h"
                    ^
           1 error generated.
           ----------------------------------------
           Command "/Users/marca/python/virtualenvs/pip/bin/python -c ...

   None of the lines above are repeated.

Author: msabramo

pip/utils/__init__.py

@@ -727,23 +727,25 @@ def call_subprocess(cmd, show_stdout=True,
     if stdout is not None:
         stdout = remove_tracebacks(console_to_str(proc.stdout.read()))
         stdout = cStringIO(stdout)
-        while 1:
-            line = stdout.readline()
-            if not line:
-                break
-            line = line.rstrip()
-            all_output.append(line + '\n')
-            if filter_stdout:
-                level = filter_stdout(line)
-                if isinstance(level, tuple):
-                    level, line = level
-                logger.log(level, line)
-                # if not logger.stdout_level_matches(level) and False:
-                #     # TODO(dstufft): Handle progress bar.
-                #     logger.show_progress()
-            else:
-                logger.debug(line)
-    else:
+        all_output = stdout.readlines()
+        if show_stdout:
+            while 1:
+                line = stdout.readline()
+                if not line:
+                    break
+                line = line.rstrip()
+                all_output.append(line + '\n')
+                if filter_stdout:
+                    level = filter_stdout(line)
+                    if isinstance(level, tuple):
+                        level, line = level
+                    logger.log(level, line)
+                    # if not logger.stdout_level_matches(level) and False:
+                    #     # TODO(dstufft): Handle progress bar.
+                    #     logger.show_progress()
+                else:
+                    logger.debug(line)
+    if not all_output:
         returned_stdout, returned_stderr = proc.communicate()
         all_output = [returned_stdout or '']
     proc.wait()

tests/functional/test_install.py

@@ -454,7 +454,7 @@ def test_install_global_option_using_editable(script, tmpdir):
         'install', '--global-option=--version', '-e',
         '%[email protected]#egg=anyjson' % local_checkout(url, tmpdir.join("cache"))
     )
-    assert '0.2.5\n' in result.stdout
+    assert 'Successfully installed anyjson' in result.stdout
 
 
 @pytest.mark.network