plot causes weird error "invalid numeric constant"

I discovered something strange when using plot from PyPlot:

``` julia
julia> 1.0
1.0
julia> using PyPlot
julia> 1.0
1.0
julia> plot([1,2,3])
1-element Any Array:
PyObject
julia> 1.0
ERROR: syntax: invalid numeric constant 1.0
```

Any ideas?

Version info:

```
Julia Version 0.2.0-prerelease+3183
Commit 8752713 2013-08-12 13:11:09 UTC
Platform Info:
System: Linux (x86_64-linux-gnu)
WORD_SIZE: 64
BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY)
LAPACK: libopenblas
LIBM: libopenlibm
```

Reproduce the error using Julia 0.2, PyPlot, and the plot([1,2,3]) entry point shown in the report. Investigate why evaluating 1.0 fails only after plotting, and verify that subsequent numeric evaluation works without the invalid numeric constant error.

Scritto dal modello di indicizzazione a partire dal testo della issue.