Only use Python3 in CI builds if requested explicitly

It looks like Travis has some old version of Python 3 which can't handle
interpolating an integer into a byte string -- expr b"wtf %d" % (5)
fails with whatever is on Travis, but works fine in Python 3.7

1 files changed, 4 insertions, 2 deletions

diff --git a/src/scripts/ci_build.py b/src/scripts/ci_build.py
index c74e4eba6..0c288a540 100755
--- a/src/scripts/ci_build.py
+++ b/src/scripts/ci_build.py
@@ -325,14 +325,16 @@ def main(args=None):
 
     target = args[1]
 
+    py_interp = 'python'
+
     use_python2 = have_prog('python2')
 
     if options.use_python3 is None:
         use_python3 = have_prog('python3')
     else:
         use_python3 = options.use_python3
-
-    py_interp = 'python3' if use_python3 else 'python'
+        if use_python3:
+            py_interp = 'python3'
 
     if options.cc_bin is None:
         if options.cc == 'gcc':