upip: expandhome(): Call uos.getenv() only if there's something to expand.

pfalcon · pfalcon · commit c06f693ac3f8 · 2016-10-08T00:36:24.000+03:00
To work on baremetal targets without getenv().
diff --git a/upip/upip.py b/upip/upip.py
@@ -89,8 +89,9 @@ def install_tar(f, prefix):
     return meta
 
 def expandhome(s):
-    h = os.getenv("HOME")
-    s = s.replace("~/", h + "/")
+    if "~/" in s:
+        h = os.getenv("HOME")
+        s = s.replace("~/", h + "/")
     return s
 
 import ussl
