Decode utf-8 from subprocess.Popen

We use subprocess.Popen directly in these scripts rather than
run_command. We need to decode the output so that we get strings
back and not bytes.

Change-Id: Ie967ceac77ecb898cab24827644b981eed22e141
diff --git a/jeepyb/cmd/notify_impact.py b/jeepyb/cmd/notify_impact.py
index 1cc76c9..5b402f5 100644
--- a/jeepyb/cmd/notify_impact.py
+++ b/jeepyb/cmd/notify_impact.py
@@ -244,7 +244,8 @@
     cmd = ['git',
            '--git-dir=' + GERRIT_GIT_DIR + '/' + args.project + '.git',
            'log', '--no-merges', args.commit + '^1..' + args.commit]
-    return subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()[0]
+    return subprocess.Popen(
+        cmd, stdout=subprocess.PIPE).communicate()[0].decode('utf-8')
 
 
 def main():
diff --git a/jeepyb/cmd/update_blueprint.py b/jeepyb/cmd/update_blueprint.py
index 0b1e44c..22efa84 100644
--- a/jeepyb/cmd/update_blueprint.py
+++ b/jeepyb/cmd/update_blueprint.py
@@ -111,9 +111,12 @@
     git_dir_arg = '--git-dir={base_dir}/{project}.git'.format(
         base_dir=GERRIT_GIT_DIR,
         project=args.project)
-    git_log = subprocess.Popen(['git', git_dir_arg, 'log', '--no-merges',
-                                args.commit + '^1..' + args.commit],
-                               stdout=subprocess.PIPE).communicate()[0]
+    git_log = subprocess.Popen(
+        [
+            'git', git_dir_arg, 'log', '--no-merges',
+            args.commit + '^1..' + args.commit
+        ],
+        stdout=subprocess.PIPE).communicate()[0].decode('utf-8')
 
     change = args.change
     if '~' in change:
diff --git a/jeepyb/cmd/update_bug.py b/jeepyb/cmd/update_bug.py
index 0278aaa..64fa536 100644
--- a/jeepyb/cmd/update_bug.py
+++ b/jeepyb/cmd/update_bug.py
@@ -335,7 +335,8 @@
     cmd = ['git',
            '--git-dir=' + GERRIT_GIT_DIR + '/' + args.project + '.git',
            'log', '--no-merges', args.commit + '^1..' + args.commit]
-    return subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()[0]
+    return subprocess.Popen(
+        cmd, stdout=subprocess.PIPE).communicate()[0].decode('utf-8')
 
 
 def main():